diff --git a/browser/components/shell/nsGNOMEShellService.cpp b/browser/components/shell/nsGNOMEShellService.cpp
index 13b21eaa797c..f264fbc6432a 100644
--- a/browser/components/shell/nsGNOMEShellService.cpp
+++ b/browser/components/shell/nsGNOMEShellService.cpp
@@ -23,11 +23,11 @@
 #include "nsIProcess.h"
 #include "nsServiceManagerUtils.h"
 #include "nsComponentManagerUtils.h"
-#include "nsIDOMElement.h"
 #include "nsIImageLoadingContent.h"
 #include "imgIRequest.h"
 #include "imgIContainer.h"
 #include "mozilla/Sprintf.h"
+#include "mozilla/dom/Element.h"
 #if defined(MOZ_WIDGET_GTK)
 #include "nsIImageToPixbuf.h"
 #endif
@@ -411,7 +411,7 @@ WriteImage(const nsCString& aPath, imgIContainer* aImage)
 }
 
 NS_IMETHODIMP
-nsGNOMEShellService::SetDesktopBackground(nsIDOMElement* aElement,
+nsGNOMEShellService::SetDesktopBackground(dom::Element* aElement,
                                           int32_t aPosition,
                                           const nsACString& aImageName)
 {
diff --git a/browser/components/shell/nsIShellService.idl b/browser/components/shell/nsIShellService.idl
index 33ab9e8d6ef3..adf0beafb378 100644
--- a/browser/components/shell/nsIShellService.idl
+++ b/browser/components/shell/nsIShellService.idl
@@ -5,9 +5,10 @@
 
 #include "nsISupports.idl"
 
-interface nsIDOMElement;
 interface nsIFile;
 
+webidl Element;
+
 [scriptable, uuid(2d1a95e4-5bd8-4eeb-b0a8-c1455fd2a357)]
 interface nsIShellService : nsISupports
 {
@@ -58,7 +59,7 @@ interface nsIShellService : nsISupports
      * @param aImageName    The image name. Equivalent to the leaf name of the
      *                      location.href.
      */
-  void setDesktopBackground(in nsIDOMElement aElement,
+  void setDesktopBackground(in Element aElement,
                             in long aPosition,
                             in ACString aImageName);
 
diff --git a/browser/components/shell/nsMacShellService.cpp b/browser/components/shell/nsMacShellService.cpp
index 0c0c8cb700f0..5dc35eaad814 100644
--- a/browser/components/shell/nsMacShellService.cpp
+++ b/browser/components/shell/nsMacShellService.cpp
@@ -22,10 +22,13 @@
 #include "nsString.h"
 #include "nsIDocShell.h"
 #include "nsILoadContext.h"
+#include "mozilla/dom/Element.h"
 
 #include <CoreFoundation/CoreFoundation.h>
 #include <ApplicationServices/ApplicationServices.h>
 
+using mozilla::dom::Element;
+
 #define NETWORK_PREFPANE NS_LITERAL_CSTRING("/System/Library/PreferencePanes/Network.prefPane")
 #define DESKTOP_PREFPANE NS_LITERAL_CSTRING("/System/Library/PreferencePanes/DesktopScreenEffectsPref.prefPane")
 
@@ -97,7 +100,7 @@ nsMacShellService::SetDefaultBrowser(bool aClaimAllTypes, bool aForAllUsers)
 }
 
 NS_IMETHODIMP
-nsMacShellService::SetDesktopBackground(nsIDOMElement* aElement,
+nsMacShellService::SetDesktopBackground(Element* aElement,
                                         int32_t aPosition,
                                         const nsACString& aImageName)
 {
@@ -112,11 +115,7 @@ nsMacShellService::SetDesktopBackground(nsIDOMElement* aElement,
   rv = imageContent->GetCurrentURI(getter_AddRefs(imageURI));
   NS_ENSURE_SUCCESS(rv, rv);
 
-  // We need the referer URI for nsIWebBrowserPersist::saveURI
-  nsCOMPtr<nsIContent> content = do_QueryInterface(aElement, &rv);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  nsIURI *docURI = content->OwnerDoc()->GetDocumentURI();
+  nsIURI *docURI = aElement->OwnerDoc()->GetDocumentURI();
   if (!docURI)
     return NS_ERROR_FAILURE;
 
@@ -149,14 +148,14 @@ nsMacShellService::SetDesktopBackground(nsIDOMElement* aElement,
   wbp->SetProgressListener(this);
 
   nsCOMPtr<nsILoadContext> loadContext;
-  nsCOMPtr<nsISupports> container = content->OwnerDoc()->GetContainer();
+  nsCOMPtr<nsISupports> container = aElement->OwnerDoc()->GetContainer();
   nsCOMPtr<nsIDocShell> docShell = do_QueryInterface(container);
   if (docShell) {
     loadContext = do_QueryInterface(docShell);
   }
 
   return wbp->SaveURI(imageURI, 0,
-                      docURI, content->OwnerDoc()->GetReferrerPolicy(),
+                      docURI, aElement->OwnerDoc()->GetReferrerPolicy(),
                       nullptr, nullptr,
                       mBackgroundFile, loadContext);
 }
diff --git a/browser/components/shell/nsWindowsShellService.cpp b/browser/components/shell/nsWindowsShellService.cpp
index b6ff42dfd5a4..05e02e0e9167 100644
--- a/browser/components/shell/nsWindowsShellService.cpp
+++ b/browser/components/shell/nsWindowsShellService.cpp
@@ -33,6 +33,7 @@
 #include "nsIURLFormatter.h"
 #include "nsXULAppAPI.h"
 #include "mozilla/WindowsVersion.h"
+#include "mozilla/dom/Element.h"
 
 #include "windows.h"
 #include "shellapi.h"
@@ -575,12 +576,11 @@ WriteBitmap(nsIFile* aFile, imgIContainer* aImage)
 }
 
 NS_IMETHODIMP
-nsWindowsShellService::SetDesktopBackground(nsIDOMElement* aElement,
+nsWindowsShellService::SetDesktopBackground(dom::Element* aElement,
                                             int32_t aPosition,
                                             const nsACString& aImageName)
 {
-  nsCOMPtr<nsIContent> content(do_QueryInterface(aElement));
-  if (!content || !content->IsHTMLElement(nsGkAtoms::img)) {
+  if (!aElement || !aElement->IsHTMLElement(nsGkAtoms::img)) {
     // XXX write background loading stuff!
     return NS_ERROR_NOT_AVAILABLE;
   }
diff --git a/docshell/base/LoadContext.cpp b/docshell/base/LoadContext.cpp
index e1785fe23835..f437bdc91190 100644
--- a/docshell/base/LoadContext.cpp
+++ b/docshell/base/LoadContext.cpp
@@ -8,6 +8,7 @@
 #include "mozilla/BasePrincipal.h"
 #include "mozilla/LoadContext.h"
 #include "mozilla/Preferences.h"
+#include "mozilla/dom/Element.h"
 #include "mozilla/dom/ScriptSettings.h" // for AutoJSAPI
 #include "nsContentUtils.h"
 #include "xpcpublic.h"
@@ -60,9 +61,9 @@ LoadContext::GetTopWindow(mozIDOMWindowProxy**)
 }
 
 NS_IMETHODIMP
-LoadContext::GetTopFrameElement(nsIDOMElement** aElement)
+LoadContext::GetTopFrameElement(dom::Element** aElement)
 {
-  nsCOMPtr<nsIDOMElement> element = do_QueryReferent(mTopFrameElement);
+  nsCOMPtr<dom::Element> element = do_QueryReferent(mTopFrameElement);
   element.forget(aElement);
   return NS_OK;
 }
diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index 52e8e2be9b8d..5a7f94dcbdb5 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -13079,7 +13079,7 @@ nsDocShell::GetTopWindow(mozIDOMWindowProxy** aWindow)
 }
 
 NS_IMETHODIMP
-nsDocShell::GetTopFrameElement(nsIDOMElement** aElement)
+nsDocShell::GetTopFrameElement(Element** aElement)
 {
   *aElement = nullptr;
   nsCOMPtr<nsPIDOMWindowOuter> win = GetWindow();
@@ -13093,8 +13093,7 @@ nsDocShell::GetTopFrameElement(nsIDOMElement** aElement)
   // GetFrameElementInternal, /not/ GetScriptableFrameElement -- if |top| is
   // inside <iframe mozbrowser>, we want to return the iframe, not null.
   // And we want to cross the content/chrome boundary.
-  nsCOMPtr<nsIDOMElement> elt =
-    do_QueryInterface(top->GetFrameElementInternal());
+  RefPtr<Element> elt = top->GetFrameElementInternal();
   elt.forget(aElement);
   return NS_OK;
 }
diff --git a/docshell/base/nsDocShell.h b/docshell/base/nsDocShell.h
index 2fe4a69441ba..7ff0f7040d7b 100644
--- a/docshell/base/nsDocShell.h
+++ b/docshell/base/nsDocShell.h
@@ -232,7 +232,7 @@ public:
   // are shared with nsIDocShell (appID, etc.) and can't be declared twice.
   NS_IMETHOD GetAssociatedWindow(mozIDOMWindowProxy**) override;
   NS_IMETHOD GetTopWindow(mozIDOMWindowProxy**) override;
-  NS_IMETHOD GetTopFrameElement(nsIDOMElement**) override;
+  NS_IMETHOD GetTopFrameElement(mozilla::dom::Element**) override;
   NS_IMETHOD GetNestedFrameId(uint64_t*) override;
   NS_IMETHOD GetIsContent(bool*) override;
   NS_IMETHOD GetUsePrivateBrowsing(bool*) override;
diff --git a/docshell/base/nsILoadContext.idl b/docshell/base/nsILoadContext.idl
index 539b3de7c680..96c6e4709fa4 100644
--- a/docshell/base/nsILoadContext.idl
+++ b/docshell/base/nsILoadContext.idl
@@ -7,7 +7,8 @@
 #include "nsISupports.idl"
 
 interface mozIDOMWindowProxy;
-interface nsIDOMElement;
+
+webidl Element;
 
 [ref] native OriginAttributes(mozilla::OriginAttributes);
 
@@ -52,7 +53,7 @@ interface nsILoadContext : nsISupports
    * Note that topFrameElement may be in chrome even when the nsILoadContext is
    * associated with content.
    */
-  readonly attribute nsIDOMElement topFrameElement;
+  readonly attribute Element topFrameElement;
 
   /**
    * If this LoadContext corresponds to a nested remote iframe, we don't have
diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index 1af27597fb47..943580e511b9 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -9700,13 +9700,12 @@ nsContentUtils::GetPresentationURL(nsIDocShell* aDocShell, nsAString& aPresentat
   }
 
   nsCOMPtr<nsILoadContext> loadContext(do_QueryInterface(aDocShell));
-  nsCOMPtr<nsIDOMElement> topFrameElement;
-  loadContext->GetTopFrameElement(getter_AddRefs(topFrameElement));
-  if (!topFrameElement) {
+  RefPtr<Element> topFrameElt;
+  loadContext->GetTopFrameElement(getter_AddRefs(topFrameElt));
+  if (!topFrameElt) {
     return;
   }
 
-  nsCOMPtr<Element> topFrameElt = do_QueryInterface(topFrameElement);
   topFrameElt->GetAttribute(NS_LITERAL_STRING("mozpresentation"), aPresentationUrl);
 }
 
diff --git a/dom/chrome-webidl/ChannelWrapper.webidl b/dom/chrome-webidl/ChannelWrapper.webidl
index f4c28d9006a6..6ba3b06978fb 100644
--- a/dom/chrome-webidl/ChannelWrapper.webidl
+++ b/dom/chrome-webidl/ChannelWrapper.webidl
@@ -294,6 +294,9 @@ interface ChannelWrapper : EventTarget {
    * For cross-process requests, the <browser> or <iframe> element to which the
    * content loading this request belongs. For requests that don't originate
    * from a remote browser, this is null.
+   *
+   * This is not an Element because those are by default only exposed in
+   * Window, but we're exposed in System.
    */
   [Cached, Pure]
   readonly attribute nsISupports? browserElement;
diff --git a/dom/ipc/TabParent.cpp b/dom/ipc/TabParent.cpp
index db3e4aa2fc24..53ea95a0bcc2 100644
--- a/dom/ipc/TabParent.cpp
+++ b/dom/ipc/TabParent.cpp
@@ -3225,9 +3225,9 @@ public:
   }
   NS_IMETHOD GetAssociatedWindow(mozIDOMWindowProxy**) NO_IMPL
   NS_IMETHOD GetTopWindow(mozIDOMWindowProxy**) NO_IMPL
-  NS_IMETHOD GetTopFrameElement(nsIDOMElement** aElement) override
+  NS_IMETHOD GetTopFrameElement(Element** aElement) override
   {
-    nsCOMPtr<nsIDOMElement> elem = do_QueryInterface(mElement);
+    nsCOMPtr<Element> elem = mElement;
     elem.forget(aElement);
     return NS_OK;
   }
diff --git a/netwerk/base/nsISecureBrowserUI.idl b/netwerk/base/nsISecureBrowserUI.idl
index 396aa42f827c..a2782d79b142 100644
--- a/netwerk/base/nsISecureBrowserUI.idl
+++ b/netwerk/base/nsISecureBrowserUI.idl
@@ -7,7 +7,6 @@
 #include "nsISupports.idl"
 
 interface mozIDOMWindowProxy;
-interface nsIDOMElement;
 interface nsIDocShell;
 
 [scriptable, uuid(718c662a-f810-4a80-a6c9-0b1810ecade2)]
diff --git a/parser/html/nsIParserUtils.idl b/parser/html/nsIParserUtils.idl
index c915bbd4d655..e4f56a4b2ad3 100644
--- a/parser/html/nsIParserUtils.idl
+++ b/parser/html/nsIParserUtils.idl
@@ -4,10 +4,10 @@
 
 #include "nsISupports.idl"
 
-interface nsIDOMElement;
 interface nsIURI;
 
 webidl DocumentFragment;
+webidl Element;
 
 /**
  * Non-Web HTML parser functionality to Firefox extensions and XULRunner apps. 
@@ -125,7 +125,7 @@ interface nsIParserUtils : nsISupports
 				 in unsigned long flags,
 				 in boolean isXML,
 				 in nsIURI baseURI,
-				 in nsIDOMElement element);
+				 in Element element);
 
 };
 
diff --git a/parser/html/nsIScriptableUnescapeHTML.idl b/parser/html/nsIScriptableUnescapeHTML.idl
index a87d404e0937..8e05e6b7d81a 100644
--- a/parser/html/nsIScriptableUnescapeHTML.idl
+++ b/parser/html/nsIScriptableUnescapeHTML.idl
@@ -5,10 +5,10 @@
 
 #include "nsISupports.idl"
 
-interface nsIDOMElement;
 interface nsIURI;
 
 webidl DocumentFragment;
+webidl Element;
 
 /**
  * This interface is OBSOLETE and exists solely for legacy extensions.
@@ -44,7 +44,7 @@ interface nsIScriptableUnescapeHTML : nsISupports
   DocumentFragment parseFragment(in AString fragment,
                                  in boolean isXML,
                                  in nsIURI baseURI,
-                                 in nsIDOMElement element);
+                                 in Element element);
 };
 
 %{ C++
diff --git a/parser/html/nsParserUtils.cpp b/parser/html/nsParserUtils.cpp
index 21c20552e32d..99386238781e 100644
--- a/parser/html/nsParserUtils.cpp
+++ b/parser/html/nsParserUtils.cpp
@@ -6,6 +6,7 @@
 #include "nsParserUtils.h"
 #include "NullPrincipal.h"
 #include "mozilla/dom/DocumentFragment.h"
+#include "mozilla/dom/Element.h"
 #include "mozilla/dom/ScriptLoader.h"
 #include "nsAttrName.h"
 #include "nsAutoPtr.h"
@@ -19,7 +20,6 @@
 #include "nsIContent.h"
 #include "nsIContentSink.h"
 #include "nsIDOMDocument.h"
-#include "nsIDOMElement.h"
 #include "nsIDOMNode.h"
 #include "nsIDTD.h"
 #include "nsIDocument.h"
@@ -107,7 +107,7 @@ NS_IMETHODIMP
 nsParserUtils::ParseFragment(const nsAString& aFragment,
                              bool aIsXML,
                              nsIURI* aBaseURI,
-                             nsIDOMElement* aContextElement,
+                             Element* aContextElement,
                              DocumentFragment** aReturn)
 {
   return nsParserUtils::ParseFragment(
@@ -119,16 +119,14 @@ nsParserUtils::ParseFragment(const nsAString& aFragment,
                              uint32_t aFlags,
                              bool aIsXML,
                              nsIURI* aBaseURI,
-                             nsIDOMElement* aContextElement,
+                             Element* aContextElement,
                              DocumentFragment** aReturn)
 {
   NS_ENSURE_ARG(aContextElement);
   *aReturn = nullptr;
 
   nsCOMPtr<nsIDocument> document;
-  nsCOMPtr<nsINode> contextNode;
-  contextNode = do_QueryInterface(aContextElement);
-  document = contextNode->OwnerDoc();
+  document = aContextElement->OwnerDoc();
 
   nsAutoScriptBlockerSuppressNodeRemoved autoBlocker;
 
diff --git a/toolkit/components/extensions/webrequest/ChannelWrapper.cpp b/toolkit/components/extensions/webrequest/ChannelWrapper.cpp
index 44dfda2e1d9d..9dea06c1b43c 100644
--- a/toolkit/components/extensions/webrequest/ChannelWrapper.cpp
+++ b/toolkit/components/extensions/webrequest/ChannelWrapper.cpp
@@ -19,6 +19,7 @@
 #include "mozilla/ErrorNames.h"
 #include "mozilla/ResultExtensions.h"
 #include "mozilla/Unused.h"
+#include "mozilla/dom/Element.h"
 #include "mozilla/dom/Event.h"
 #include "mozilla/dom/TabParent.h"
 #include "nsIContentPolicy.h"
@@ -334,11 +335,11 @@ ChannelWrapper::GetLoadContext() const
   return nullptr;
 }
 
-already_AddRefed<nsIDOMElement>
+already_AddRefed<Element>
 ChannelWrapper::GetBrowserElement() const
 {
   if (nsCOMPtr<nsILoadContext> ctxt = GetLoadContext()) {
-    nsCOMPtr<nsIDOMElement> elem;
+    RefPtr<Element> elem;
     if (NS_SUCCEEDED(ctxt->GetTopFrameElement(getter_AddRefs(elem)))) {
       return elem.forget();
     }
diff --git a/toolkit/components/extensions/webrequest/ChannelWrapper.h b/toolkit/components/extensions/webrequest/ChannelWrapper.h
index 8ba238991070..7435a5b00d06 100644
--- a/toolkit/components/extensions/webrequest/ChannelWrapper.h
+++ b/toolkit/components/extensions/webrequest/ChannelWrapper.h
@@ -36,14 +36,14 @@
 { 0xc06162d2, 0xb803, 0x43b4, \
   { 0xaa, 0x31, 0xcf, 0x69, 0x7f, 0x93, 0x68, 0x1c } }
 
-class nsIDOMElement;
 class nsILoadContext;
 class nsITraceableChannel;
 
 namespace mozilla {
 namespace dom {
   class nsIContentParent;
-}
+  class Element;
+} // namespace dom
 namespace extensions {
 
 namespace detail {
@@ -206,7 +206,7 @@ public:
 
   already_AddRefed<nsILoadContext> GetLoadContext() const;
 
-  already_AddRefed<nsIDOMElement> GetBrowserElement() const;
+  already_AddRefed<dom::Element> GetBrowserElement() const;
 
 
   bool CanModify() const;
diff --git a/uriloader/prefetch/OfflineCacheUpdateParent.cpp b/uriloader/prefetch/OfflineCacheUpdateParent.cpp
index 9f7816da19c7..2f344734850c 100644
--- a/uriloader/prefetch/OfflineCacheUpdateParent.cpp
+++ b/uriloader/prefetch/OfflineCacheUpdateParent.cpp
@@ -7,6 +7,7 @@
 
 #include "BackgroundUtils.h"
 #include "mozilla/BasePrincipal.h"
+#include "mozilla/dom/Element.h"
 #include "mozilla/dom/TabParent.h"
 #include "mozilla/ipc/URIUtils.h"
 #include "mozilla/Unused.h"
@@ -209,7 +210,7 @@ OfflineCacheUpdateParent::GetTopWindow(mozIDOMWindowProxy** aTopWindow)
 }
 
 NS_IMETHODIMP
-OfflineCacheUpdateParent::GetTopFrameElement(nsIDOMElement** aElement)
+OfflineCacheUpdateParent::GetTopFrameElement(dom::Element** aElement)
 {
     return NS_ERROR_NOT_IMPLEMENTED;
 }
diff --git a/widget/cocoa/nsStandaloneNativeMenu.mm b/widget/cocoa/nsStandaloneNativeMenu.mm
index 82f78bffc7f8..452bfbabdc55 100644
--- a/widget/cocoa/nsStandaloneNativeMenu.mm
+++ b/widget/cocoa/nsStandaloneNativeMenu.mm
@@ -7,10 +7,12 @@
 
 #include "nsStandaloneNativeMenu.h"
 #include "nsMenuUtilsX.h"
-#include "nsIDOMElement.h"
 #include "nsIMutationObserver.h"
 #include "nsGkAtoms.h"
 #include "nsObjCExceptions.h"
+#include "mozilla/dom/Element.h"
+
+using mozilla::dom::Element;
 
 
 NS_IMPL_ISUPPORTS_INHERITED(nsStandaloneNativeMenu, nsMenuGroupOwnerX,
@@ -28,24 +30,21 @@ nsStandaloneNativeMenu::~nsStandaloneNativeMenu()
 }
 
 NS_IMETHODIMP
-nsStandaloneNativeMenu::Init(nsIDOMElement * aDOMElement)
+nsStandaloneNativeMenu::Init(Element* aElement)
 {
   NS_ASSERTION(mMenu == nullptr, "nsNativeMenu::Init - mMenu not null!");
 
-  nsresult rv;
+  NS_ENSURE_ARG(aElement);
 
-  nsCOMPtr<nsIContent> content = do_QueryInterface(aDOMElement, &rv);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  if (!content->IsAnyOfXULElements(nsGkAtoms::menu, nsGkAtoms::menupopup))
+  if (!aElement->IsAnyOfXULElements(nsGkAtoms::menu, nsGkAtoms::menupopup))
     return NS_ERROR_FAILURE;
 
-  rv = nsMenuGroupOwnerX::Create(content->AsElement());
+  nsresult rv = nsMenuGroupOwnerX::Create(aElement);
   if (NS_FAILED(rv))
     return rv;
 
   mMenu = new nsMenuX();
-  rv = mMenu->Create(this, this, content);
+  rv = mMenu->Create(this, this, aElement);
   if (NS_FAILED(rv)) {
     delete mMenu;
     mMenu = nullptr;
diff --git a/widget/cocoa/nsSystemStatusBarCocoa.mm b/widget/cocoa/nsSystemStatusBarCocoa.mm
index 522da71451de..6a229d35a342 100644
--- a/widget/cocoa/nsSystemStatusBarCocoa.mm
+++ b/widget/cocoa/nsSystemStatusBarCocoa.mm
@@ -9,22 +9,24 @@
 #include "nsSystemStatusBarCocoa.h"
 #include "nsStandaloneNativeMenu.h"
 #include "nsObjCExceptions.h"
-#include "nsIDOMElement.h"
+#include "mozilla/dom/Element.h"
+
+using mozilla::dom::Element;
 
 NS_IMPL_ISUPPORTS(nsSystemStatusBarCocoa, nsISystemStatusBar)
 
 NS_IMETHODIMP
-nsSystemStatusBarCocoa::AddItem(nsIDOMElement* aDOMElement)
+nsSystemStatusBarCocoa::AddItem(Element* aElement)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
   RefPtr<nsStandaloneNativeMenu> menu = new nsStandaloneNativeMenu();
-  nsresult rv = menu->Init(aDOMElement);
+  nsresult rv = menu->Init(aElement);
   if (NS_FAILED(rv)) {
     return rv;
   }
 
-  nsCOMPtr<nsISupports> keyPtr = aDOMElement;
+  nsCOMPtr<nsISupports> keyPtr = aElement;
   mItems.Put(keyPtr, new StatusItem(menu));
 
   return NS_OK;
@@ -33,11 +35,11 @@ nsSystemStatusBarCocoa::AddItem(nsIDOMElement* aDOMElement)
 }
 
 NS_IMETHODIMP
-nsSystemStatusBarCocoa::RemoveItem(nsIDOMElement* aDOMElement)
+nsSystemStatusBarCocoa::RemoveItem(Element* aElement)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
-  mItems.Remove(aDOMElement);
+  mItems.Remove(aElement);
 
   return NS_OK;
 
diff --git a/widget/nsIStandaloneNativeMenu.idl b/widget/nsIStandaloneNativeMenu.idl
index 4de2025c8e31..a40b3f8840d7 100644
--- a/widget/nsIStandaloneNativeMenu.idl
+++ b/widget/nsIStandaloneNativeMenu.idl
@@ -4,7 +4,7 @@
 
 #include "nsISupports.idl"
 
-interface nsIDOMElement;
+webidl Element;
 
 /**
  * Platform-independent interface to platform native menu objects.
@@ -18,7 +18,7 @@ interface nsIStandaloneNativeMenu : nsISupports
    *
    * @param aDOMElement A XUL DOM element of tag type |menu| or |menupopup|.
    */
-  void init(in nsIDOMElement aDOMElement);
+  void init(in Element aElement);
 
   /**
    * This method must be called before the menu is opened and displayed to the
diff --git a/widget/nsISystemStatusBar.idl b/widget/nsISystemStatusBar.idl
index 9db8015199a7..51aa457a085b 100644
--- a/widget/nsISystemStatusBar.idl
+++ b/widget/nsISystemStatusBar.idl
@@ -4,7 +4,7 @@
 
 #include "nsISupports.idl"
 
-interface nsIDOMElement;
+webidl Element;
 
 /**
  * Allow applications to interface with the Mac OS X system status bar.
@@ -25,12 +25,12 @@ interface nsISystemStatusBar : nsISupports
    *                        a menu with the contents of the menupopup.
    *                        The menu label is not shown.
    */
-  void addItem(in nsIDOMElement aDOMMenuElement);
+  void addItem(in Element aMenuElement);
 
   /**
    * Remove a previously-added item from the menu bar. Calling this with an
    * element that has not been added before will be silently ignored.
    * @param aDOMMenuElement The XUL menu element that you called addItem with.
    */
-  void removeItem(in nsIDOMElement aDOMMenuElement);
+  void removeItem(in Element aMenuElement);
 };
diff --git a/xpcom/system/nsIGeolocationProvider.idl b/xpcom/system/nsIGeolocationProvider.idl
index 29044266dae4..27de63f054dd 100644
--- a/xpcom/system/nsIGeolocationProvider.idl
+++ b/xpcom/system/nsIGeolocationProvider.idl
@@ -8,7 +8,6 @@
 
 interface nsIURI;
 interface nsIDOMWindow;
-interface nsIDOMElement;
 interface nsIDOMGeoPosition;
 interface nsIGeolocationPrompt;
 
diff --git a/xpfe/appshell/nsContentTreeOwner.cpp b/xpfe/appshell/nsContentTreeOwner.cpp
index 5ad7cbba1fc0..deceac5244eb 100644
--- a/xpfe/appshell/nsContentTreeOwner.cpp
+++ b/xpfe/appshell/nsContentTreeOwner.cpp
@@ -451,7 +451,7 @@ NS_IMETHODIMP nsContentTreeOwner::SetStatusWithContext(uint32_t aStatusType,
     {
     case STATUS_LINK:
       {
-        nsCOMPtr<nsIDOMElement> element = do_QueryInterface(aStatusContext);
+        nsCOMPtr<dom::Element> element = do_QueryInterface(aStatusContext);
         xulBrowserWindow->SetOverLink(aStatusText, element);
         break;
       }
diff --git a/xpfe/appshell/nsIXULBrowserWindow.idl b/xpfe/appshell/nsIXULBrowserWindow.idl
index ee1740daa57d..4d5f9824bfae 100644
--- a/xpfe/appshell/nsIXULBrowserWindow.idl
+++ b/xpfe/appshell/nsIXULBrowserWindow.idl
@@ -10,7 +10,6 @@
 
 interface nsIBrowser;
 interface nsIRequest;
-interface nsIDOMElement;
 interface nsIInputStream;
 interface nsIDocShell;
 interface nsIFrameLoaderOwner;
@@ -18,6 +17,8 @@ interface nsITabParent;
 interface nsIPrincipal;
 interface mozIDOMWindowProxy;
 
+webidl Element;
+
 /**
  * The nsIXULBrowserWindow supplies the methods that may be called from the
  * internals of the browser area to tell the containing xul window to update
@@ -30,7 +31,7 @@ interface nsIXULBrowserWindow : nsISupports
    * Tells the object implementing this function what link we are currently
    * over.
    */
-  void setOverLink(in AString link, in nsIDOMElement element);
+  void setOverLink(in AString link, in Element element);
 
   /**
    * Determines the appropriate target for a link.