1 files changed, 39 insertions, 10 deletions

diff --git a/dom/base/nsINode.h b/dom/base/nsINode.h
index a0d972f80..0f882445f 100644
--- a/dom/base/nsINode.h
+++ b/dom/base/nsINode.h
@@ -126,9 +126,28 @@ enum {
 
   NODE_IS_EDITABLE =                      NODE_FLAG_BIT(7),
 
-  // For all Element nodes, NODE_MAY_HAVE_CLASS is guaranteed to be set if the
-  // node in fact has a class, but may be set even if it doesn't.
-  NODE_MAY_HAVE_CLASS =                   NODE_FLAG_BIT(8),
+  // This node was created by layout as native anonymous content. This
+  // generally corresponds to things created by nsIAnonymousContentCreator,
+  // though there are exceptions (svg:use content does not have this flag
+  // set, and any non-nsIAnonymousContentCreator callers of
+  // SetIsNativeAnonymousRoot also get this flag).
+  //
+  // One very important aspect here is that this node is not transitive over
+  // the subtree (if you want that, use NODE_IS_IN_NATIVE_ANONYMOUS_SUBTREE).
+  // If Gecko code somewhere attaches children to a node with this bit set,
+  // the children will not have the bit themselves unless the calling code sets
+  // it explicitly. This means that XBL content bound to NAC doesn't get this
+  // bit, nor do nodes inserted by editor.
+  //
+  // For now, this bit exists primarily to control style inheritance behavior,
+  // since the nodes for which we set it are often used to implement pseudo-
+  // elements, which need to inherit style from a script-visible element.
+  //
+  // A more general principle for this bit might be this: If the node is entirely
+  // a detail of layout, is not script-observable in any way, and other engines
+  // might accomplish the same task with a nodeless layout frame, then the node
+  // should have this bit set.
+  NODE_IS_NATIVE_ANONYMOUS =              NODE_FLAG_BIT(8),
 
   // Whether the node participates in a shadow tree.
   NODE_IS_IN_SHADOW_TREE =                NODE_FLAG_BIT(9),
@@ -1212,6 +1231,15 @@ public:
   }
 
   /**
+   * Returns true if |this| is native anonymous (i.e. created by
+   * nsIAnonymousContentCreator);
+   */
+  bool IsNativeAnonymous() const
+  {
+    return HasFlag(NODE_IS_NATIVE_ANONYMOUS);
+  }
+
+  /**
    * Returns true if |this| or any of its ancestors is native anonymous.
    */
   bool IsInNativeAnonymousSubtree() const
@@ -1343,10 +1371,11 @@ public:
 
 protected:
   nsIURI* GetExplicitBaseURI() const {
-    if (HasExplicitBaseURI()) {
-      return static_cast<nsIURI*>(GetProperty(nsGkAtoms::baseURIProperty));
+    if (!HasProperties()) {
+      return nullptr;
     }
-    return nullptr;
+
+    return static_cast<nsIURI*>(GetProperty(nsGkAtoms::baseURIProperty));
   }
 
 public:
@@ -1549,6 +1578,8 @@ private:
     // cases lie for nsXMLElement, such as when the node has been moved between
     // documents with different id mappings.
     ElementHasID,
+    // Set if the element might have a class.
+    ElementMayHaveClass,
     // Set if the element might have inline style.
     ElementMayHaveStyle,
     // Set if the element has a name attribute set.
@@ -1567,8 +1598,6 @@ private:
     // Maybe set if the node is a root of a subtree
     // which needs to be kept in the purple buffer.
     NodeIsPurpleRoot,
-    // Set if the node has an explicit base URI stored
-    NodeHasExplicitBaseURI,
     // Set if the element has some style states locked
     ElementHasLockedStyleStates,
     // Set if element has pointer locked
@@ -1645,6 +1674,8 @@ public:
     { SetBoolFlag(NodeHasRenderingObservers, aValue); }
   bool IsContent() const { return GetBoolFlag(NodeIsContent); }
   bool HasID() const { return GetBoolFlag(ElementHasID); }
+  bool MayHaveClass() const { return GetBoolFlag(ElementMayHaveClass); }
+  void SetMayHaveClass() { SetBoolFlag(ElementMayHaveClass); }
   bool MayHaveStyle() const { return GetBoolFlag(ElementMayHaveStyle); }
   bool HasName() const { return GetBoolFlag(ElementHasName); }
   bool MayHaveContentEditableAttr() const
@@ -1774,8 +1805,6 @@ protected:
   void ClearHasName() { ClearBoolFlag(ElementHasName); }
   void SetMayHaveContentEditableAttr()
     { SetBoolFlag(ElementMayHaveContentEditableAttr); }
-  bool HasExplicitBaseURI() const { return GetBoolFlag(NodeHasExplicitBaseURI); }
-  void SetHasExplicitBaseURI() { SetBoolFlag(NodeHasExplicitBaseURI); }
   void SetHasLockedStyleStates() { SetBoolFlag(ElementHasLockedStyleStates); }
   void ClearHasLockedStyleStates() { ClearBoolFlag(ElementHasLockedStyleStates); }
   bool HasLockedStyleStates() const