diff --git a/dom/webidl/XSLTProcessor.webidl b/dom/webidl/XSLTProcessor.webidl
index 2215a98feae3..69b195ded7d9 100644
--- a/dom/webidl/XSLTProcessor.webidl
+++ b/dom/webidl/XSLTProcessor.webidl
@@ -88,13 +88,11 @@ interface XSLTProcessor {
      * the processor use the default-value for all parameters as specified in
      * the stylesheet.
      */
-    [Throws]
     undefined clearParameters();
 
     /**
      * Remove all parameters and stylesheets from this XSLTProcessor.
      */
-    [Throws]
     undefined reset();
 
     /**
diff --git a/dom/xslt/xml/txXMLParser.cpp b/dom/xslt/xml/txXMLParser.cpp
index 1d576cdbacfc..779e198fb1da 100644
--- a/dom/xslt/xml/txXMLParser.cpp
+++ b/dom/xslt/xml/txXMLParser.cpp
@@ -12,15 +12,16 @@
 #include "nsNetUtil.h"
 #include "nsIURI.h"
 
-using namespace mozilla;
 using namespace mozilla::dom;
 
-Result<txXPathNode, nsresult> txParseDocumentFromURI(const nsAString& aHref,
-                                                     const txXPathNode& aLoader,
-                                                     nsAString& aErrMsg) {
+nsresult txParseDocumentFromURI(const nsAString& aHref,
+                                const txXPathNode& aLoader, nsAString& aErrMsg,
+                                txXPathNode** aResult) {
+  NS_ENSURE_ARG_POINTER(aResult);
+  *aResult = nullptr;
   nsCOMPtr<nsIURI> documentURI;
   nsresult rv = NS_NewURI(getter_AddRefs(documentURI), aHref);
-  NS_ENSURE_SUCCESS(rv, Err(rv));
+  NS_ENSURE_SUCCESS(rv, rv);
 
   Document* loaderDocument = txXPathNativeNode::getDocument(aLoader);
 
@@ -31,7 +32,7 @@ Result<txXPathNode, nsresult> txParseDocumentFromURI(const nsAString& aHref,
 
   // Raw pointer, we want the resulting txXPathNode to hold a reference to
   // the document.
-  nsCOMPtr<Document> theDocument;
+  Document* theDocument = nullptr;
   nsAutoSyncOperation sync(loaderDocument,
                            SyncOperationBehavior::eSuspendInput);
   rv = nsSyncLoadService::LoadDocument(
@@ -39,14 +40,20 @@ Result<txXPathNode, nsresult> txParseDocumentFromURI(const nsAString& aHref,
       loaderDocument->NodePrincipal(),
       nsILoadInfo::SEC_REQUIRE_CORS_INHERITS_SEC_CONTEXT, loadGroup,
       loaderDocument->CookieJarSettings(), true,
-      loaderDocument->GetReferrerPolicy(), getter_AddRefs(theDocument));
+      loaderDocument->GetReferrerPolicy(), &theDocument);
 
   if (NS_FAILED(rv)) {
     aErrMsg.AppendLiteral("Document load of ");
     aErrMsg.Append(aHref);
     aErrMsg.AppendLiteral(" failed.");
-    return Err(rv);
+    return NS_FAILED(rv) ? rv : NS_ERROR_FAILURE;
   }
 
-  return txXPathNode(theDocument);
+  *aResult = txXPathNativeNode::createXPathNode(theDocument);
+  if (!*aResult) {
+    NS_RELEASE(theDocument);
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
 }
diff --git a/dom/xslt/xml/txXMLParser.h b/dom/xslt/xml/txXMLParser.h
index ba800a7b2b39..83f22215062b 100644
--- a/dom/xslt/xml/txXMLParser.h
+++ b/dom/xslt/xml/txXMLParser.h
@@ -10,11 +10,6 @@
 
 class txXPathNode;
 
-namespace mozilla {
-template <typename V, typename E>
-class Result;
-}  // namespace mozilla
-
 /**
  * API to load XML files into DOM datastructures.
  * Parsing is either done by expat, or by expat via the syncloaderservice
@@ -24,7 +19,9 @@ class Result;
  * Parse a document from the aHref location, with referrer URI on behalf
  * of the document aLoader.
  */
-mozilla::Result<txXPathNode, nsresult> txParseDocumentFromURI(
-    const nsAString& aHref, const txXPathNode& aLoader, nsAString& aErrMsg);
+extern "C" nsresult txParseDocumentFromURI(const nsAString& aHref,
+                                           const txXPathNode& aLoader,
+                                           nsAString& aErrMsg,
+                                           txXPathNode** aResult);
 
 #endif
diff --git a/dom/xslt/xpath/XPathExpression.cpp b/dom/xslt/xpath/XPathExpression.cpp
index cf226a39c540..0706763d79f2 100644
--- a/dom/xslt/xpath/XPathExpression.cpp
+++ b/dom/xslt/xpath/XPathExpression.cpp
@@ -23,9 +23,9 @@ namespace mozilla::dom {
 
 class EvalContextImpl : public txIEvalContext {
  public:
-  EvalContextImpl(txXPathNode&& aContextNode, uint32_t aContextPosition,
+  EvalContextImpl(const txXPathNode& aContextNode, uint32_t aContextPosition,
                   uint32_t aContextSize, txResultRecycler* aRecycler)
-      : mContextNode(std::move(aContextNode)),
+      : mContextNode(aContextNode),
         mContextPosition(aContextPosition),
         mContextSize(aContextSize),
         mLastError(NS_OK),
@@ -121,15 +121,15 @@ already_AddRefed<XPathResult> XPathExpression::EvaluateWithContext(
     return nullptr;
   }
 
-  Maybe<txXPathNode> contextNode =
-      txXPathNativeNode::createXPathNode(&aContextNode);
+  UniquePtr<txXPathNode> contextNode(
+      txXPathNativeNode::createXPathNode(&aContextNode));
   if (!contextNode) {
     aRv.Throw(NS_ERROR_FAILURE);
     return nullptr;
   }
 
-  EvalContextImpl eContext(contextNode.extract(), aContextPosition,
-                           aContextSize, mRecycler);
+  EvalContextImpl eContext(*contextNode, aContextPosition, aContextSize,
+                           mRecycler);
   RefPtr<txAExprResult> exprResult;
   aRv = mExpression->evaluate(&eContext, getter_AddRefs(exprResult));
   if (aRv.Failed()) {
diff --git a/dom/xslt/xpath/XPathResult.cpp b/dom/xslt/xpath/XPathResult.cpp
index 73dd610156f6..ba2c1b31fcd7 100644
--- a/dom/xslt/xpath/XPathResult.cpp
+++ b/dom/xslt/xpath/XPathResult.cpp
@@ -238,13 +238,13 @@ nsresult XPathResult::GetExprResult(txAExprResult** aExprResult) {
   RefPtr<txNodeSet> nodeSet = new txNodeSet(nullptr);
   uint32_t i, count = mResultNodes.Length();
   for (i = 0; i < count; ++i) {
-    Maybe<txXPathNode> node(
+    UniquePtr<txXPathNode> node(
         txXPathNativeNode::createXPathNode(mResultNodes[i]));
     if (!node) {
       return NS_ERROR_OUT_OF_MEMORY;
     }
 
-    nodeSet->append(node.extract());
+    nodeSet->append(*node);
   }
 
   NS_ADDREF(*aExprResult = nodeSet);
diff --git a/dom/xslt/xpath/txMozillaXPathTreeWalker.cpp b/dom/xslt/xpath/txMozillaXPathTreeWalker.cpp
index 6fdd33f05531..8150d7307e5a 100644
--- a/dom/xslt/xpath/txMozillaXPathTreeWalker.cpp
+++ b/dom/xslt/xpath/txMozillaXPathTreeWalker.cpp
@@ -23,8 +23,8 @@
 #include <stdint.h>
 #include <algorithm>
 
-using namespace mozilla;
 using namespace mozilla::dom;
+using mozilla::Maybe;
 
 txXPathTreeWalker::txXPathTreeWalker(const txXPathTreeWalker& aOther) = default;
 
@@ -228,6 +228,24 @@ bool txXPathTreeWalker::moveToParent() {
   return true;
 }
 
+txXPathNode::txXPathNode(const txXPathNode& aNode)
+    : mNode(aNode.mNode),
+      mRefCountRoot(aNode.mRefCountRoot),
+      mIndex(aNode.mIndex) {
+  MOZ_COUNT_CTOR(txXPathNode);
+  if (mRefCountRoot) {
+    NS_ADDREF(Root());
+  }
+}
+
+txXPathNode::~txXPathNode() {
+  MOZ_COUNT_DTOR(txXPathNode);
+  if (mRefCountRoot) {
+    nsINode* root = Root();
+    NS_RELEASE(root);
+  }
+}
+
 /* static */
 bool txXPathNodeUtils::getAttr(const txXPathNode& aNode, nsAtom* aLocalName,
                                int32_t aNSID, nsAString& aValue) {
@@ -425,8 +443,8 @@ bool txXPathNodeUtils::isWhitespace(const txXPathNode& aNode) {
 }
 
 /* static */
-txXPathNode txXPathNodeUtils::getOwnerDocument(const txXPathNode& aNode) {
-  return txXPathNode(aNode.mNode->OwnerDoc());
+txXPathNode* txXPathNodeUtils::getOwnerDocument(const txXPathNode& aNode) {
+  return new txXPathNode(aNode.mNode->OwnerDoc());
 }
 
 const char gPrintfFmt[] = "id0x%" PRIxPTR;
@@ -436,8 +454,7 @@ const char gPrintfFmtAttr[] = "id0x%" PRIxPTR "-%010i";
 nsresult txXPathNodeUtils::getXSLTId(const txXPathNode& aNode,
                                      const txXPathNode& aBase,
                                      nsAString& aResult) {
-  uintptr_t nodeid =
-      ((uintptr_t)aNode.mNode.get()) - ((uintptr_t)aBase.mNode.get());
+  uintptr_t nodeid = ((uintptr_t)aNode.mNode) - ((uintptr_t)aBase.mNode);
   if (!aNode.isAttribute()) {
     CopyASCIItoUTF16(nsPrintfCString(gPrintfFmt, nodeid), aResult);
   } else {
@@ -568,7 +585,16 @@ int txXPathNodeUtils::comparePosition(const txXPathNode& aNode,
 }
 
 /* static */
-Maybe<txXPathNode> txXPathNativeNode::createXPathNode(nsINode* aNode) {
+txXPathNode* txXPathNativeNode::createXPathNode(nsIContent* aContent,
+                                                bool aKeepRootAlive) {
+  nsINode* root = aKeepRootAlive ? txXPathNode::RootOf(aContent) : nullptr;
+
+  return new txXPathNode(aContent, txXPathNode::eContent, root);
+}
+
+/* static */
+txXPathNode* txXPathNativeNode::createXPathNode(nsINode* aNode,
+                                                bool aKeepRootAlive) {
   uint16_t nodeType = aNode->NodeType();
   if (nodeType == nsINode::ATTRIBUTE_NODE) {
     auto* attr = static_cast<Attr*>(aNode);
@@ -576,30 +602,42 @@ Maybe<txXPathNode> txXPathNativeNode::createXPathNode(nsINode* aNode) {
     NodeInfo* nodeInfo = attr->NodeInfo();
     Element* parent = attr->GetElement();
     if (!parent) {
-      return Nothing();
+      return nullptr;
     }
 
+    nsINode* root = aKeepRootAlive ? txXPathNode::RootOf(parent) : nullptr;
+
     uint32_t i, total = parent->GetAttrCount();
     for (i = 0; i < total; ++i) {
       const nsAttrName* name = parent->GetAttrNameAt(i);
       if (nodeInfo->Equals(name->LocalName(), name->NamespaceID())) {
-        return Some(txXPathNode(parent, i));
+        return new txXPathNode(parent, i, root);
       }
     }
 
     NS_ERROR("Couldn't find the attribute in its parent!");
 
-    return Nothing();
+    return nullptr;
   }
 
   uint32_t index;
+  nsINode* root = aKeepRootAlive ? aNode : nullptr;
+
   if (nodeType == nsINode::DOCUMENT_NODE) {
     index = txXPathNode::eDocument;
   } else {
     index = txXPathNode::eContent;
+    if (root) {
+      root = txXPathNode::RootOf(root);
+    }
   }
 
-  return Some(txXPathNode(aNode, index));
+  return new txXPathNode(aNode, index, root);
+}
+
+/* static */
+txXPathNode* txXPathNativeNode::createXPathNode(Document* aDocument) {
+  return new txXPathNode(aDocument);
 }
 
 /* static */
diff --git a/dom/xslt/xpath/txNodeSet.cpp b/dom/xslt/xpath/txNodeSet.cpp
index a8ba2a7b29dd..9baf006906ab 100644
--- a/dom/xslt/xpath/txNodeSet.cpp
+++ b/dom/xslt/xpath/txNodeSet.cpp
@@ -82,12 +82,12 @@ txNodeSet::~txNodeSet() {
   }
 }
 
-nsresult txNodeSet::add(txXPathNode&& aNode) {
+nsresult txNodeSet::add(const txXPathNode& aNode) {
   NS_ASSERTION(mDirection == kForward,
                "only append(aNode) is supported on reversed nodesets");
 
   if (isEmpty()) {
-    return append(std::move(aNode));
+    return append(aNode);
   }
 
   bool dupe;
@@ -113,7 +113,7 @@ nsresult txNodeSet::add(txXPathNode&& aNode) {
     memmove((void*)(pos + 1), pos, moveSize * sizeof(txXPathNode));
   }
 
-  new (pos) txXPathNode(std::move(aNode));
+  new (pos) txXPathNode(aNode);
   ++mEnd;
 
   return NS_OK;
@@ -295,19 +295,19 @@ nsresult txNodeSet::add(const txNodeSet& aNodes, transferOp aTransfer,
  * order info operations will be performed.
  */
 
-nsresult txNodeSet::append(txXPathNode&& aNode) {
+nsresult txNodeSet::append(const txXPathNode& aNode) {
   if (!ensureGrowSize(1)) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
 
   if (mDirection == kForward) {
-    new (mEnd) txXPathNode(std::move(aNode));
+    new (mEnd) txXPathNode(aNode);
     ++mEnd;
 
     return NS_OK;
   }
 
-  new (--mStart) txXPathNode(std::move(aNode));
+  new (--mStart) txXPathNode(aNode);
 
   return NS_OK;
 }
diff --git a/dom/xslt/xpath/txNodeSet.h b/dom/xslt/xpath/txNodeSet.h
index 5885799923a1..8c5e805d6bcf 100644
--- a/dom/xslt/xpath/txNodeSet.h
+++ b/dom/xslt/xpath/txNodeSet.h
@@ -44,8 +44,7 @@ class txNodeSet : public txAExprResult {
    * @param  aNode the txXPathNode to add to the NodeSet
    * @return errorcode.
    */
-  nsresult add(const txXPathNode& aNode) { return add(txXPathNode(aNode)); }
-  nsresult add(txXPathNode&& aNode);
+  nsresult add(const txXPathNode& aNode);
 
   /**
    * Adds the nodes in specified NodeSet to this NodeSet. The resulting
@@ -73,10 +72,7 @@ class txNodeSet : public txAExprResult {
    * @param  aNode the Node to append to the NodeSet
    * @return errorcode.
    */
-  nsresult append(const txXPathNode& aNode) {
-    return append(txXPathNode(aNode));
-  }
-  nsresult append(txXPathNode&& aNode);
+  nsresult append(const txXPathNode& aNode);
 
   /**
    * Appends the nodes in the specified NodeSet to the end of this NodeSet
diff --git a/dom/xslt/xpath/txXPathNode.h b/dom/xslt/xpath/txXPathNode.h
index ea7d1f6220c9..8c5d6f530838 100644
--- a/dom/xslt/xpath/txXPathNode.h
+++ b/dom/xslt/xpath/txXPathNode.h
@@ -13,70 +13,35 @@
 
 using txXPathNodeType = nsINode;
 
-/**
- * txXPathNode represents a node in XPath's data model (which is a bit different
- * from the DOM's). While XPath 1.0 has 7 node types, we essentially deal with 3
- * kinds: a document node, any other node type that is backed by an
- * implementation of nsIContent in Gecko, and attribute nodes. Because we try to
- * avoid creating actual node objects for attribute nodes in Gecko's DOM, we
- * store attribute nodes as a pointer to their owner element and an index into
- * that element's attribute node list. So to represent the 3 kinds of node we
- * need to store:
- *
- *  - a pointer to a document (a nsIDocument as a nsINode pointer)
- *  - a pointer to a nsIContent object (as a nsINode pointer)
- *  - a pointer to a nsIContent object (a nsIContent as a nsINode pointer) and
- *    an index
- *
- * So we make txXPathNode store a |nsCOMPtr<nsINode>| and a uint32_t for the
- * index. To be able to distinguish between the attribute nodes and other nodes
- * we store a flag value for the other nodes in the index. To be able to quickly
- * cast from the nsINode pointer to a nsIDocument or nsIContent pointer we
- * actually use 2 different flag values (see txXPathNode::PositionType).
- *
- * We provide 2 fast constructors for txXPathNode, one that takes a nsIContent
- * and one that takes a nsIDocument, since for those kinds of nodes we can
- * simply store the pointer and the relevant flag value. For attribute nodes, or
- * if you have just a nsINode pointer, then there is a helper function
- * (txXPathNativeNode::createXPathNode) that either picks the right flag value
- * or the correct index (for attribute nodes) when creating the txXPathNode.
- */
 class txXPathNode {
  public:
-  explicit txXPathNode(const txXPathNode& aNode)
-      : mNode(aNode.mNode), mIndex(aNode.mIndex) {
-    MOZ_COUNT_CTOR(txXPathNode);
-  }
-  txXPathNode(txXPathNode&& aNode)
-      : mNode(std::move(aNode.mNode)), mIndex(aNode.mIndex) {
-    MOZ_COUNT_CTOR(txXPathNode);
-  }
-
-  explicit txXPathNode(mozilla::dom::Document* aDocument)
-      : mNode(aDocument), mIndex(eDocument) {
-    MOZ_COUNT_CTOR(txXPathNode);
-  }
-  explicit txXPathNode(nsIContent* aContent)
-      : mNode(aContent), mIndex(eContent) {
-    MOZ_COUNT_CTOR(txXPathNode);
-  }
-
-  txXPathNode& operator=(txXPathNode&& aOther) = default;
   bool operator==(const txXPathNode& aNode) const;
   bool operator!=(const txXPathNode& aNode) const { return !(*this == aNode); }
-  ~txXPathNode() { MOZ_COUNT_DTOR(txXPathNode); }
+  ~txXPathNode();
 
  private:
+  friend class txNodeSet;
   friend class txXPathNativeNode;
   friend class txXPathNodeUtils;
   friend class txXPathTreeWalker;
 
-  txXPathNode(nsINode* aNode, uint32_t aIndex) : mNode(aNode), mIndex(aIndex) {
+  txXPathNode(const txXPathNode& aNode);
+
+  explicit txXPathNode(mozilla::dom::Document* aDocument)
+      : mNode(aDocument), mRefCountRoot(0), mIndex(eDocument) {
     MOZ_COUNT_CTOR(txXPathNode);
   }
+  txXPathNode(nsINode* aNode, uint32_t aIndex, nsINode* aRoot)
+      : mNode(aNode), mRefCountRoot(aRoot ? 1 : 0), mIndex(aIndex) {
+    MOZ_COUNT_CTOR(txXPathNode);
+    if (aRoot) {
+      NS_ADDREF(aRoot);
+    }
+  }
 
   static nsINode* RootOf(nsINode* aNode) { return aNode->SubtreeRoot(); }
   nsINode* Root() const { return RootOf(mNode); }
+  nsINode* GetRootToAddRef() const { return mRefCountRoot ? Root() : nullptr; }
 
   bool isDocument() const { return mIndex == eDocument; }
   bool isContent() const { return mIndex == eContent; }
@@ -84,20 +49,18 @@ class txXPathNode {
 
   nsIContent* Content() const {
     NS_ASSERTION(isContent() || isAttribute(), "wrong type");
-    return static_cast<nsIContent*>(mNode.get());
+    return static_cast<nsIContent*>(mNode);
   }
   mozilla::dom::Document* Document() const {
     NS_ASSERTION(isDocument(), "wrong type");
-    return static_cast<mozilla::dom::Document*>(mNode.get());
+    return static_cast<mozilla::dom::Document*>(mNode);
   }
 
-  enum PositionType : uint32_t {
-    eDocument = UINT32_MAX,
-    eContent = eDocument - 1
-  };
+  enum PositionType { eDocument = (1 << 30), eContent = eDocument - 1 };
 
-  nsCOMPtr<nsINode> mNode;
-  uint32_t mIndex;
+  nsINode* mNode;
+  uint32_t mRefCountRoot : 1;
+  uint32_t mIndex : 31;
 };
 
 class txNamespaceManager {
diff --git a/dom/xslt/xpath/txXPathTreeWalker.h b/dom/xslt/xpath/txXPathTreeWalker.h
index e6bc14ae9984..6b74b1e18d8f 100644
--- a/dom/xslt/xpath/txXPathTreeWalker.h
+++ b/dom/xslt/xpath/txXPathTreeWalker.h
@@ -60,7 +60,7 @@ class txXPathNodeUtils {
   static uint16_t getNodeType(const txXPathNode& aNode);
   static void appendNodeValue(const txXPathNode& aNode, nsAString& aResult);
   static bool isWhitespace(const txXPathNode& aNode);
-  static txXPathNode getOwnerDocument(const txXPathNode& aNode);
+  static txXPathNode* getOwnerDocument(const txXPathNode& aNode);
   static int32_t getUniqueIdentifier(const txXPathNode& aNode);
   static nsresult getXSLTId(const txXPathNode& aNode, const txXPathNode& aBase,
                             nsAString& aResult);
@@ -86,10 +86,19 @@ class txXPathNodeUtils {
 
 class txXPathNativeNode {
  public:
-  static mozilla::Maybe<txXPathNode> createXPathNode(nsINode* aNode);
+  static txXPathNode* createXPathNode(nsINode* aNode,
+                                      bool aKeepRootAlive = false);
+  static txXPathNode* createXPathNode(nsIContent* aContent,
+                                      bool aKeepRootAlive = false);
+  static txXPathNode* createXPathNode(mozilla::dom::Document* aDocument);
   static nsINode* getNode(const txXPathNode& aNode);
   static nsIContent* getContent(const txXPathNode& aNode);
   static mozilla::dom::Document* getDocument(const txXPathNode& aNode);
+  static void addRef(const txXPathNode& aNode) { NS_ADDREF(aNode.mNode); }
+  static void release(const txXPathNode& aNode) {
+    nsINode* node = aNode.mNode;
+    NS_RELEASE(node);
+  }
 };
 
 inline const txXPathNode& txXPathTreeWalker::getCurrentPosition() const {
@@ -114,8 +123,21 @@ inline void txXPathTreeWalker::getNodeName(nsAString& aName) const {
 }
 
 inline void txXPathTreeWalker::moveTo(const txXPathTreeWalker& aWalker) {
+  nsINode* root = nullptr;
+  if (mPosition.mRefCountRoot) {
+    root = mPosition.Root();
+  }
   mPosition.mIndex = aWalker.mPosition.mIndex;
+  mPosition.mRefCountRoot = aWalker.mPosition.mRefCountRoot;
   mPosition.mNode = aWalker.mPosition.mNode;
+  nsINode* newRoot = nullptr;
+  if (mPosition.mRefCountRoot) {
+    newRoot = mPosition.Root();
+  }
+  if (root != newRoot) {
+    NS_IF_ADDREF(newRoot);
+    NS_IF_RELEASE(root);
+  }
 }
 
 inline bool txXPathTreeWalker::isOnNode(const txXPathNode& aNode) const {
@@ -125,7 +147,12 @@ inline bool txXPathTreeWalker::isOnNode(const txXPathNode& aNode) const {
 /* static */
 inline int32_t txXPathNodeUtils::getUniqueIdentifier(const txXPathNode& aNode) {
   MOZ_ASSERT(!aNode.isAttribute(), "Not implemented for attributes.");
-  return NS_PTR_TO_INT32(aNode.mNode.get());
+  return NS_PTR_TO_INT32(aNode.mNode);
+}
+
+/* static */
+inline void txXPathNodeUtils::release(txXPathNode* aNode) {
+  NS_RELEASE(aNode->mNode);
 }
 
 /* static */
diff --git a/dom/xslt/xslt/txEXSLTFunctions.cpp b/dom/xslt/xslt/txEXSLTFunctions.cpp
index e61b47dcad03..d58ca33b5374 100644
--- a/dom/xslt/xslt/txEXSLTFunctions.cpp
+++ b/dom/xslt/xslt/txEXSLTFunctions.cpp
@@ -73,7 +73,11 @@ static nsresult convertRtfToNode(txIEvalContext* aContext,
   NS_ENSURE_SUCCESS(rv, rv);
 
   // The txResultTreeFragment will own this.
-  aRtf->setNode(new txXPathNode(domFragment));
+  const txXPathNode* node =
+      txXPathNativeNode::createXPathNode(domFragment, true);
+  NS_ENSURE_TRUE(node, NS_ERROR_OUT_OF_MEMORY);
+
+  aRtf->setNode(node);
 
   return NS_OK;
 }
@@ -91,7 +95,8 @@ static nsresult createTextNode(txIEvalContext* aContext, nsString& aValue,
   nsresult rv = text->SetText(aValue, false);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  *aResult = new txXPathNode(text);
+  *aResult = txXPathNativeNode::createXPathNode(text, true);
+  NS_ENSURE_TRUE(*aResult, NS_ERROR_OUT_OF_MEMORY);
 
   return NS_OK;
 }
@@ -121,10 +126,11 @@ static nsresult createAndAddToResult(nsAtom* aName, const nsAString& aValue,
     return error.StealNSResult();
   }
 
-  Maybe<txXPathNode> xpathNode(txXPathNativeNode::createXPathNode(elem));
+  UniquePtr<txXPathNode> xpathNode(
+      txXPathNativeNode::createXPathNode(elem, true));
   NS_ENSURE_TRUE(xpathNode, NS_ERROR_OUT_OF_MEMORY);
 
-  aResultSet->append(xpathNode.extract());
+  aResultSet->append(*xpathNode);
 
   return NS_OK;
 }
@@ -699,7 +705,8 @@ nsresult txEXSLTRegExFunctionCall::evaluate(txIEvalContext* aContext,
       UniquePtr<txXPathNode> node;
       for (nsIContent* result = docFrag->GetFirstChild(); result;
            result = result->GetNextSibling()) {
-        rv = resultSet->add(txXPathNode(result));
+        node = WrapUnique(txXPathNativeNode::createXPathNode(result, true));
+        rv = resultSet->add(*node);
         NS_ENSURE_SUCCESS(rv, rv);
       }
 
diff --git a/dom/xslt/xslt/txExecutionState.cpp b/dom/xslt/xslt/txExecutionState.cpp
index d05c3a70b79c..a3cfddac1c62 100644
--- a/dom/xslt/xslt/txExecutionState.cpp
+++ b/dom/xslt/xslt/txExecutionState.cpp
@@ -14,12 +14,14 @@
 #include "txURIUtils.h"
 #include "txXMLParser.h"
 
-using namespace mozilla;
+using mozilla::UniquePtr;
+using mozilla::Unused;
+using mozilla::WrapUnique;
 
 const int32_t txExecutionState::kMaxRecursionDepth = 20000;
 
 nsresult txLoadedDocumentsHash::init(const txXPathNode& aSource) {
-  mSourceDocument = Some(txXPathNodeUtils::getOwnerDocument(aSource));
+  mSourceDocument = WrapUnique(txXPathNodeUtils::getOwnerDocument(aSource));
 
   nsAutoString baseURI;
   nsresult rv = txXPathNodeUtils::getBaseURI(*mSourceDocument, baseURI);
@@ -37,12 +39,24 @@ nsresult txLoadedDocumentsHash::init(const txXPathNode& aSource) {
   // txMozillaXSLTProcessor::TransformToFragment) it makes more sense to return
   // the real root of the source tree, which is the node where the transform
   // started.
-  WithEntryHandle(baseURI, [&aSource](auto&& entry) {
-    entry.Insert(txLoadedDocumentEntry{txXPathNode(aSource)});
-  });
+  PutEntry(baseURI)->mDocument = WrapUnique(
+      txXPathNativeNode::createXPathNode(txXPathNativeNode::getNode(aSource)));
   return NS_OK;
 }
 
+txLoadedDocumentsHash::~txLoadedDocumentsHash() {
+  if (mSourceDocument) {
+    nsAutoString baseURI;
+    nsresult rv = txXPathNodeUtils::getBaseURI(*mSourceDocument, baseURI);
+    if (NS_SUCCEEDED(rv)) {
+      txLoadedDocumentEntry* entry = GetEntry(baseURI);
+      if (entry) {
+        delete entry->mDocument.release();
+      }
+    }
+  }
+}
+
 txExecutionState::txExecutionState(txStylesheet* aStylesheet,
                                    bool aDisableLoads)
     : mOutputHandler(nullptr),
@@ -344,24 +358,27 @@ const txXPathNode* txExecutionState::retrieveDocument(const nsAString& aUri) {
           ("Retrieve Document %s", NS_LossyConvertUTF16toASCII(aUri).get()));
 
   // try to get already loaded document
-  const Variant<txXPathNode, nsresult>& result =
-      mLoadedDocuments.LookupOrInsertWith(aUri, [&] {
-        // open URI
-        nsAutoString errMsg;
-        // XXX we should get the loader from the actual node
-        // triggering the load, but this will do for the time being
-        Result<txXPathNode, nsresult> loadResult = txParseDocumentFromURI(
-            aUri, *mLoadedDocuments.mSourceDocument, errMsg);
+  txLoadedDocumentEntry* entry = mLoadedDocuments.PutEntry(aUri);
+  if (!entry) {
+    return nullptr;
+  }
 
-        if (loadResult.isErr()) {
-          nsresult rv = loadResult.unwrapErr();
-          receiveError(
-              u"Couldn't load document '"_ns + aUri + u"': "_ns + errMsg, rv);
-          return txLoadedDocumentEntry(rv);
-        }
-        return txLoadedDocumentEntry(loadResult.unwrap());
-      });
-  return result.is<txXPathNode>() ? &result.as<txXPathNode>() : nullptr;
+  if (!entry->mDocument && !entry->LoadingFailed()) {
+    // open URI
+    nsAutoString errMsg;
+    // XXX we should get the loader from the actual node
+    // triggering the load, but this will do for the time being
+    entry->mLoadResult =
+        txParseDocumentFromURI(aUri, *mLoadedDocuments.mSourceDocument, errMsg,
+                               getter_Transfers(entry->mDocument));
+
+    if (entry->LoadingFailed()) {
+      receiveError(u"Couldn't load document '"_ns + aUri + u"': "_ns + errMsg,
+                   entry->mLoadResult);
+    }
+  }
+
+  return entry->mDocument.get();
 }
 
 nsresult txExecutionState::getKeyNodes(const txExpandedName& aKeyName,
diff --git a/dom/xslt/xslt/txExecutionState.h b/dom/xslt/xslt/txExecutionState.h
index 89f5a1e19fca..7a314cf8a4b8 100644
--- a/dom/xslt/xslt/txExecutionState.h
+++ b/dom/xslt/xslt/txExecutionState.h
@@ -23,18 +23,41 @@ class txAOutputHandlerFactory;
 class txAXMLEventHandler;
 class txInstruction;
 
-using txLoadedDocumentEntry = mozilla::Variant<txXPathNode, nsresult>;
-
-class txLoadedDocumentsHash
-    : public nsTHashMap<nsString, txLoadedDocumentEntry> {
+class txLoadedDocumentEntry : public nsStringHashKey {
  public:
-  txLoadedDocumentsHash() : nsTHashMap<nsString, txLoadedDocumentEntry>(4) {}
+  explicit txLoadedDocumentEntry(KeyTypePointer aStr)
+      : nsStringHashKey(aStr), mLoadResult(NS_OK) {}
+  txLoadedDocumentEntry(txLoadedDocumentEntry&& aOther)
+      : nsStringHashKey(std::move(aOther)),
+        mDocument(std::move(aOther.mDocument)),
+        mLoadResult(std::move(aOther.mLoadResult)) {
+    NS_ERROR("We're horked.");
+  }
+  ~txLoadedDocumentEntry() {
+    if (mDocument) {
+      txXPathNodeUtils::release(mDocument.get());
+    }
+  }
+  bool LoadingFailed() {
+    NS_ASSERTION(NS_SUCCEEDED(mLoadResult) || !mDocument,
+                 "Load failed but we still got a document?");
 
+    return NS_FAILED(mLoadResult);
+  }
+
+  mozilla::UniquePtr<txXPathNode> mDocument;
+  nsresult mLoadResult;
+};
+
+class txLoadedDocumentsHash : public nsTHashtable<txLoadedDocumentEntry> {
+ public:
+  txLoadedDocumentsHash() : nsTHashtable<txLoadedDocumentEntry>(4) {}
+  ~txLoadedDocumentsHash();
   [[nodiscard]] nsresult init(const txXPathNode& aSource);
 
  private:
   friend class txExecutionState;
-  mozilla::Maybe<txXPathNode> mSourceDocument;
+  mozilla::UniquePtr<txXPathNode> mSourceDocument;
 };
 
 class txExecutionState : public txIMatchContext {
diff --git a/dom/xslt/xslt/txMozillaXSLTProcessor.cpp b/dom/xslt/xslt/txMozillaXSLTProcessor.cpp
index 067c6a4563a5..2508056d3236 100644
--- a/dom/xslt/xslt/txMozillaXSLTProcessor.cpp
+++ b/dom/xslt/xslt/txMozillaXSLTProcessor.cpp
@@ -5,7 +5,6 @@
 
 #include "txMozillaXSLTProcessor.h"
 #include "nsError.h"
-#include "mozilla/AutoRestore.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/Document.h"
 #include "nsIStringBundle.h"
@@ -329,11 +328,9 @@ txMozillaXSLTProcessor::AddXSLTParamNamespace(const nsString& aPrefix,
 
 class txXSLTParamContext : public txIParseContext, public txIEvalContext {
  public:
-  txXSLTParamContext(txNamespaceMap* aResolver, txXPathNode&& aContext,
+  txXSLTParamContext(txNamespaceMap* aResolver, const txXPathNode& aContext,
                      txResultRecycler* aRecycler)
-      : mResolver(aResolver),
-        mContext(std::move(aContext)),
-        mRecycler(aRecycler) {}
+      : mResolver(aResolver), mContext(aContext), mRecycler(aRecycler) {}
 
   // txIParseContext
   int32_t resolveNamespacePrefix(nsAtom* aPrefix) override {
@@ -388,7 +385,7 @@ txMozillaXSLTProcessor::AddXSLTParam(const nsString& aName,
   uint16_t resultType;
   if (!aSelect.IsVoid()) {
     // Set up context
-    Maybe<txXPathNode> contextNode(
+    UniquePtr<txXPathNode> contextNode(
         txXPathNativeNode::createXPathNode(aContext));
     NS_ENSURE_TRUE(contextNode, NS_ERROR_OUT_OF_MEMORY);
 
@@ -396,7 +393,7 @@ txMozillaXSLTProcessor::AddXSLTParam(const nsString& aName,
       mRecycler = new txResultRecycler;
     }
 
-    txXSLTParamContext paramContext(&mParamNamespaceMap, contextNode.extract(),
+    txXSLTParamContext paramContext(&mParamNamespaceMap, *contextNode,
                                     mRecycler);
 
     // Parse
@@ -476,8 +473,6 @@ class nsTransformBlockerEvent : public mozilla::Runnable {
   }
 
   NS_IMETHOD Run() override {
-    MOZ_RELEASE_ASSERT(mProcessor->mState ==
-                       txMozillaXSLTProcessor::State::None);
     mProcessor->TransformToDoc(nullptr, false);
     return NS_OK;
   }
@@ -509,13 +504,6 @@ void txMozillaXSLTProcessor::ImportStylesheet(nsINode& aStyle,
     return;
   }
 
-  if (mState != State::None) {
-    aRv.ThrowInvalidStateError("Invalid call.");
-    return;
-  }
-  mozilla::AutoRestore<State> restore(mState);
-  mState = State::Compiling;
-
   MOZ_ASSERT(!mEmbeddedStylesheetRoot);
 
   mCompileResult = NS_OK;
@@ -559,21 +547,12 @@ already_AddRefed<Document> txMozillaXSLTProcessor::TransformToDocument(
     return nullptr;
   }
 
-  if (mState != State::None) {
-    aRv.ThrowInvalidStateError("Invalid call.");
-    return nullptr;
-  }
-
   nsresult rv = ensureStylesheet();
   if (NS_WARN_IF(NS_FAILED(rv))) {
     aRv.Throw(rv);
     return nullptr;
   }
 
-  MOZ_RELEASE_ASSERT(mState == State::None);
-  mozilla::AutoRestore<State> restore(mState);
-  mState = State::Transforming;
-
   mSource = aSource.CloneNode(true, aRv);
   if (aRv.Failed()) {
     return nullptr;
@@ -676,7 +655,8 @@ XSLTProcessRequest::SetTRRMode(nsIRequest::TRRMode aTRRMode) {
 
 nsresult txMozillaXSLTProcessor::TransformToDoc(Document** aResult,
                                                 bool aCreateDataDocument) {
-  Maybe<txXPathNode> sourceNode(txXPathNativeNode::createXPathNode(mSource));
+  UniquePtr<txXPathNode> sourceNode(
+      txXPathNativeNode::createXPathNode(mSource));
   if (!sourceNode) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
@@ -758,21 +738,12 @@ already_AddRefed<DocumentFragment> txMozillaXSLTProcessor::TransformToFragment(
     return nullptr;
   }
 
-  if (mState != State::None) {
-    aRv.ThrowInvalidStateError("Invalid call.");
-    return nullptr;
-  }
-
   nsresult rv = ensureStylesheet();
   if (NS_WARN_IF(NS_FAILED(rv))) {
     aRv.Throw(rv);
     return nullptr;
   }
 
-  MOZ_RELEASE_ASSERT(mState == State::None);
-  mozilla::AutoRestore<State> restore(mState);
-  mState = State::Transforming;
-
   nsCOMPtr<nsINode> source;
   if (aCloneSource) {
     source = aSource.CloneNode(true, aRv);
@@ -783,7 +754,7 @@ already_AddRefed<DocumentFragment> txMozillaXSLTProcessor::TransformToFragment(
     source = &aSource;
   }
 
-  Maybe<txXPathNode> sourceNode(txXPathNativeNode::createXPathNode(source));
+  UniquePtr<txXPathNode> sourceNode(txXPathNativeNode::createXPathNode(source));
   if (!sourceNode) {
     aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
     return nullptr;
@@ -797,7 +768,7 @@ already_AddRefed<DocumentFragment> txMozillaXSLTProcessor::TransformToFragment(
   txToFragmentHandlerFactory handlerFactory(frag);
   es.mOutputHandlerFactory = &handlerFactory;
 
-  rv = es.init(sourceNode.extract(), &mVariables);
+  rv = es.init(*sourceNode, &mVariables);
 
   // Process root of XML source document
   if (NS_SUCCEEDED(rv)) {
@@ -821,11 +792,6 @@ void txMozillaXSLTProcessor::SetParameter(const nsAString& aNamespaceURI,
                                           const nsAString& aLocalName,
                                           const XSLTParameterValue& aValue,
                                           ErrorResult& aError) {
-  if (mState != State::None) {
-    aError.ThrowInvalidStateError("Invalid call.");
-    return;
-  }
-
   if (aValue.IsNode()) {
     if (!nsContentUtils::CanCallerAccess(&aValue.GetAsNode())) {
       aError.ThrowSecurityError("Caller is not allowed to access node.");
@@ -914,11 +880,6 @@ void txMozillaXSLTProcessor::GetParameter(
 void txMozillaXSLTProcessor::RemoveParameter(const nsAString& aNamespaceURI,
                                              const nsAString& aLocalName,
                                              ErrorResult& aRv) {
-  if (mState != State::None) {
-    aRv.ThrowInvalidStateError("Invalid call.");
-    return;
-  }
-
   int32_t nsId = kNameSpaceID_Unknown;
   nsresult rv =
       nsNameSpaceManager::GetInstance()->RegisterNameSpace(aNamespaceURI, nsId);
@@ -932,21 +893,9 @@ void txMozillaXSLTProcessor::RemoveParameter(const nsAString& aNamespaceURI,
   mVariables.remove(varName);
 }
 
-void txMozillaXSLTProcessor::ClearParameters(ErrorResult& aError) {
-  if (mState != State::None) {
-    aError.ThrowInvalidStateError("Invalid call.");
-    return;
-  }
-
-  mVariables.clear();
-}
-
-void txMozillaXSLTProcessor::Reset(ErrorResult& aError) {
-  if (mState != State::None) {
-    aError.ThrowInvalidStateError("Invalid call.");
-    return;
-  }
+void txMozillaXSLTProcessor::ClearParameters() { mVariables.clear(); }
 
+void txMozillaXSLTProcessor::Reset() {
   if (mStylesheetDocument) {
     mStylesheetDocument->RemoveMutationObserver(this);
   }
@@ -1106,12 +1055,6 @@ void txMozillaXSLTProcessor::notifyError() {
 }
 
 nsresult txMozillaXSLTProcessor::ensureStylesheet() {
-  if (mState != State::None) {
-    return NS_ERROR_FAILURE;
-  }
-  mozilla::AutoRestore<State> restore(mState);
-  mState = State::Compiling;
-
   if (mStylesheet) {
     return NS_OK;
   }
@@ -1242,7 +1185,7 @@ nsresult txVariable::convert(const OwningXSLTParameterValue& aUnionValue,
 
   if (aUnionValue.IsNode()) {
     nsINode& node = aUnionValue.GetAsNode();
-    Maybe<txXPathNode> xpathNode(txXPathNativeNode::createXPathNode(&node));
+    UniquePtr<txXPathNode> xpathNode(txXPathNativeNode::createXPathNode(&node));
     if (!xpathNode) {
       return NS_ERROR_FAILURE;
     }
@@ -1256,13 +1199,13 @@ nsresult txVariable::convert(const OwningXSLTParameterValue& aUnionValue,
     const Sequence<OwningNonNull<nsINode>>& values =
         aUnionValue.GetAsNodeSequence();
     for (const auto& node : values) {
-      Maybe<txXPathNode> xpathNode(
+      UniquePtr<txXPathNode> xpathNode(
           txXPathNativeNode::createXPathNode(node.get()));
       if (!xpathNode) {
         return NS_ERROR_FAILURE;
       }
 
-      nodeSet->append(xpathNode.extract());
+      nodeSet->append(*xpathNode);
     }
     nodeSet.forget(aValue);
     return NS_OK;
diff --git a/dom/xslt/xslt/txMozillaXSLTProcessor.h b/dom/xslt/xslt/txMozillaXSLTProcessor.h
index 352d32c2255a..bb470d34154d 100644
--- a/dom/xslt/xslt/txMozillaXSLTProcessor.h
+++ b/dom/xslt/xslt/txMozillaXSLTProcessor.h
@@ -92,17 +92,17 @@ class txMozillaXSLTProcessor final : public nsIDocumentTransformer,
   static already_AddRefed<txMozillaXSLTProcessor> Constructor(
       const mozilla::dom::GlobalObject& aGlobal);
 
-  void ImportStylesheet(nsINode& aStylesheet, mozilla::ErrorResult& aRv);
+  void ImportStylesheet(nsINode& stylesheet, mozilla::ErrorResult& aRv);
   already_AddRefed<mozilla::dom::DocumentFragment> TransformToFragment(
-      nsINode& aSource, mozilla::dom::Document& aOutput,
+      nsINode& aSource, mozilla::dom::Document& aDocument,
       mozilla::ErrorResult& aRv) {
-    return TransformToFragment(aSource, true, aOutput, aRv);
+    return TransformToFragment(aSource, true, aDocument, aRv);
   }
   already_AddRefed<mozilla::dom::DocumentFragment> TransformToFragment(
       nsINode& aSource, bool aCloneSource, mozilla::dom::Document& aOutput,
       mozilla::ErrorResult& aRv);
   already_AddRefed<mozilla::dom::Document> TransformToDocument(
-      nsINode& aSource, mozilla::ErrorResult& aRv);
+      nsINode& source, mozilla::ErrorResult& aRv);
 
   void SetParameter(const nsAString& aNamespaceURI, const nsAString& aLocalName,
                     const XSLTParameterValue& aValue,
@@ -112,8 +112,8 @@ class txMozillaXSLTProcessor final : public nsIDocumentTransformer,
                     mozilla::ErrorResult& aRv);
   void RemoveParameter(const nsAString& aNamespaceURI,
                        const nsAString& aLocalName, mozilla::ErrorResult& aRv);
-  void ClearParameters(mozilla::ErrorResult& aError);
-  void Reset(mozilla::ErrorResult& aError);
+  void ClearParameters();
+  void Reset();
 
   uint32_t Flags(mozilla::dom::SystemCallerGuarantee);
   void SetFlags(uint32_t aFlags, mozilla::dom::SystemCallerGuarantee);
@@ -136,8 +136,6 @@ class txMozillaXSLTProcessor final : public nsIDocumentTransformer,
   static void Shutdown();
 
  private:
-  friend class nsTransformBlockerEvent;
-
   explicit txMozillaXSLTProcessor(nsISupports* aOwner);
   /**
    * Default destructor for txMozillaXSLTProcessor
@@ -164,13 +162,6 @@ class txMozillaXSLTProcessor final : public nsIDocumentTransformer,
   RefPtr<txResultRecycler> mRecycler;
 
   uint32_t mFlags;
-
-  enum class State {
-    None,
-    Compiling,
-    Transforming,
-  };
-  State mState = State::None;
 };
 
 extern nsresult TX_LoadSheet(nsIURI* aUri, txMozillaXSLTProcessor* aProcessor,
diff --git a/dom/xslt/xslt/txXSLTPatterns.cpp b/dom/xslt/xslt/txXSLTPatterns.cpp
index 2c78dc45026b..dc1b81e210e1 100644
--- a/dom/xslt/xslt/txXSLTPatterns.cpp
+++ b/dom/xslt/xslt/txXSLTPatterns.cpp
@@ -329,11 +329,12 @@ void txIdPattern::toString(nsAString& aDest) {
 nsresult txKeyPattern::matches(const txXPathNode& aNode,
                                txIMatchContext* aContext, bool& aMatched) {
   txExecutionState* es = (txExecutionState*)aContext->getPrivateContext();
-  txXPathNode contextDoc(txXPathNodeUtils::getOwnerDocument(aNode));
+  UniquePtr<txXPathNode> contextDoc(txXPathNodeUtils::getOwnerDocument(aNode));
+  NS_ENSURE_TRUE(contextDoc, NS_ERROR_FAILURE);
 
   RefPtr<txNodeSet> nodes;
   nsresult rv =
-      es->getKeyNodes(mName, contextDoc, mValue, true, getter_AddRefs(nodes));
+      es->getKeyNodes(mName, *contextDoc, mValue, true, getter_AddRefs(nodes));
   NS_ENSURE_SUCCESS(rv, rv);
 
   aMatched = nodes->contains(aNode);