diff --git a/dom/base/nsIContentInlines.h b/dom/base/nsIContentInlines.h
index 6f98f3b31cab..9e123c3820d4 100644
--- a/dom/base/nsIContentInlines.h
+++ b/dom/base/nsIContentInlines.h
@@ -166,6 +166,20 @@ nsINode::NodeOrAncestorHasDirAuto() const
   return AncestorHasDirAuto() || (IsElement() && AsElement()->HasDirAuto());
 }
 
+inline bool
+nsINode::IsEditable() const
+{
+  if (HasFlag(NODE_IS_EDITABLE)) {
+    // The node is in an editable contentEditable subtree.
+    return true;
+  }
+
+  nsIDocument* doc = GetUncomposedDoc();
+
+  // Check if the node is in a document and the document is in designMode.
+  return doc && doc->HasFlag(NODE_IS_EDITABLE);
+}
+
 inline bool
 nsIContent::IsActiveChildrenElement() const
 {
diff --git a/dom/base/nsINode.cpp b/dom/base/nsINode.cpp
index e42d2da66dce..27d746bfec3d 100644
--- a/dom/base/nsINode.cpp
+++ b/dom/base/nsINode.cpp
@@ -201,20 +201,6 @@ nsINode::CreateSlots()
   return new nsSlots();
 }
 
-bool
-nsINode::IsEditable() const
-{
-  if (HasFlag(NODE_IS_EDITABLE)) {
-    // The node is in an editable contentEditable subtree.
-    return true;
-  }
-
-  nsIDocument *doc = GetUncomposedDoc();
-
-  // Check if the node is in a document and the document is in designMode.
-  return doc && doc->HasFlag(NODE_IS_EDITABLE);
-}
-
 nsIContent*
 nsINode::GetTextEditorRootContent(TextEditor** aTextEditor)
 {
diff --git a/dom/base/nsINode.h b/dom/base/nsINode.h
index 890d1674def9..e7fdc9e856f9 100644
--- a/dom/base/nsINode.h
+++ b/dom/base/nsINode.h
@@ -1249,7 +1249,7 @@ public:
     }
   }
 
-  bool IsEditable() const;
+  inline bool IsEditable() const;
 
   /**
    * Returns true if |this| or any of its ancestors is native anonymous.
diff --git a/dom/svg/SVGAElement.cpp b/dom/svg/SVGAElement.cpp
index ca2c0421b488..6eac22f08785 100644
--- a/dom/svg/SVGAElement.cpp
+++ b/dom/svg/SVGAElement.cpp
@@ -14,6 +14,7 @@
 #include "nsContentUtils.h"
 #include "nsGkAtoms.h"
 #include "nsSVGString.h"
+#include "nsIContentInlines.h"
 #include "nsIURI.h"
 
 NS_IMPL_NS_NEW_NAMESPACED_SVG_ELEMENT(A)
diff --git a/editor/libeditor/EditorBase.cpp b/editor/libeditor/EditorBase.cpp
index d063a2adc61f..b88a845f95db 100644
--- a/editor/libeditor/EditorBase.cpp
+++ b/editor/libeditor/EditorBase.cpp
@@ -71,7 +71,7 @@
 #include "nsGenericHTMLElement.h"       // for nsGenericHTMLElement
 #include "nsGkAtoms.h"                  // for nsGkAtoms, nsGkAtoms::dir
 #include "nsIAbsorbingTransaction.h"    // for nsIAbsorbingTransaction
-#include "nsAtom.h"                    // for nsAtom
+#include "nsAtom.h"                     // for nsAtom
 #include "nsIContent.h"                 // for nsIContent
 #include "nsIDocument.h"                // for nsIDocument
 #include "nsIDOMEventListener.h"        // for nsIDOMEventListener
diff --git a/editor/libeditor/EditorBase.h b/editor/libeditor/EditorBase.h
index 727f2a6cb10e..109323e94462 100644
--- a/editor/libeditor/EditorBase.h
+++ b/editor/libeditor/EditorBase.h
@@ -22,6 +22,7 @@
 #include "nsCycleCollectionParticipant.h"
 #include "nsGkAtoms.h"
 #include "nsIDocument.h"                // for nsIDocument
+#include "nsIContentInlines.h"          // for nsINode::IsEditable()
 #include "nsIEditor.h"                  // for nsIEditor, etc.
 #include "nsIObserver.h"                // for NS_DECL_NSIOBSERVER, etc.
 #include "nsIPlaintextEditor.h"         // for nsIPlaintextEditor, etc.
diff --git a/editor/libeditor/WSRunObject.cpp b/editor/libeditor/WSRunObject.cpp
index f3703cb98b6a..69a8f35ccfc4 100644
--- a/editor/libeditor/WSRunObject.cpp
+++ b/editor/libeditor/WSRunObject.cpp
@@ -22,6 +22,7 @@
 #include "nsDebug.h"
 #include "nsError.h"
 #include "nsIContent.h"
+#include "nsIContentInlines.h"
 #include "nsISupportsImpl.h"
 #include "nsRange.h"
 #include "nsString.h"
diff --git a/gfx/layers/apz/src/FocusTarget.cpp b/gfx/layers/apz/src/FocusTarget.cpp
index 790781c39b90..b8b1fb56ef27 100644
--- a/gfx/layers/apz/src/FocusTarget.cpp
+++ b/gfx/layers/apz/src/FocusTarget.cpp
@@ -10,6 +10,7 @@
 #include "mozilla/dom/TabParent.h"   // for TabParent
 #include "mozilla/EventDispatcher.h" // for EventDispatcher
 #include "mozilla/layout/RenderFrameParent.h" // For RenderFrameParent
+#include "nsIContentInlines.h" // for nsINode::IsEditable()
 #include "nsIPresShell.h"  // for nsIPresShell
 #include "nsLayoutUtils.h" // for nsLayoutUtils