Bug 1413619 - Fix insertion point computation when display: contents pseudos are involved.

Tag #1375

dom/base/ChildIterator.h

@@ -58,13 +58,13 @@ public:
   // found.  This version can take shortcuts that the two-argument version
   // can't, so can be faster (and in fact can be O(1) instead of O(N) in many
   // cases).
-  bool Seek(nsIContent* aChildToFind);
+  bool Seek(const nsIContent* aChildToFind);
 
   // Looks for aChildToFind respecting insertion points until aChildToFind is found.
   // or aBound is found. If aBound is nullptr then the seek is unbounded. Returns
   // whether aChildToFind was found as an explicit child prior to encountering
   // aBound.
-  bool Seek(nsIContent* aChildToFind, nsIContent* aBound)
+  bool Seek(const nsIContent* aChildToFind, nsIContent* aBound)
   {
     // It would be nice to assert that we find aChildToFind, but bz thinks that
     // we might not find aChildToFind when called from ContentInserted
@@ -131,19 +131,29 @@ class FlattenedChildIterator : public ExplicitChildIterator
 public:
   explicit FlattenedChildIterator(const nsIContent* aParent,
                                   bool aStartAtBeginning = true)
-    : ExplicitChildIterator(aParent, aStartAtBeginning), mXBLInvolved(false)
+    : ExplicitChildIterator(aParent, aStartAtBeginning)
+    , mXBLInvolved(false)
+    , mOriginalContent(aParent)
   {
     Init(false);
   }
 
   FlattenedChildIterator(FlattenedChildIterator&& aOther)
-    : ExplicitChildIterator(Move(aOther)), mXBLInvolved(aOther.mXBLInvolved) {}
+    : ExplicitChildIterator(Move(aOther))
+    , mXBLInvolved(aOther.mXBLInvolved)
+    , mOriginalContent(aOther.mOriginalContent)
+  {}
 
   FlattenedChildIterator(const FlattenedChildIterator& aOther)
-    : ExplicitChildIterator(aOther), mXBLInvolved(aOther.mXBLInvolved) {}
+    : ExplicitChildIterator(aOther)
+    , mXBLInvolved(aOther.mXBLInvolved)
+    , mOriginalContent(aOther.mOriginalContent)
+  {}
 
   bool XBLInvolved() { return mXBLInvolved; }
 
+  const nsIContent* Parent() const { return mOriginalContent; }
+
 protected:
   /**
    * This constructor is a hack to help AllChildrenIterator which sometimes
@@ -151,7 +161,9 @@ protected:
    */
   FlattenedChildIterator(const nsIContent* aParent, uint32_t aFlags,
                          bool aStartAtBeginning = true)
-    : ExplicitChildIterator(aParent, aStartAtBeginning), mXBLInvolved(false)
+    : ExplicitChildIterator(aParent, aStartAtBeginning)
+    , mXBLInvolved(false)
+    , mOriginalContent(aParent)
   {
     bool ignoreXBL = aFlags & nsIContent::eAllButXBL;
     Init(ignoreXBL);
@@ -162,6 +174,8 @@ protected:
   // For certain optimizations, nsCSSFrameConstructor needs to know if the
   // child list of the element that we're iterating matches its .childNodes.
   bool mXBLInvolved;
+
+  const nsIContent* mOriginalContent;
 };
 
 /**
@@ -179,12 +193,11 @@ public:
   AllChildrenIterator(const nsIContent* aNode, uint32_t aFlags,
                       bool aStartAtBeginning = true) :
     FlattenedChildIterator(aNode, aFlags, aStartAtBeginning),
-    mOriginalContent(aNode), mAnonKidsIdx(aStartAtBeginning ? UINT32_MAX : 0),
+    mAnonKidsIdx(aStartAtBeginning ? UINT32_MAX : 0),
     mFlags(aFlags), mPhase(aStartAtBeginning ? eAtBegin : eAtEnd) { }
 
   AllChildrenIterator(AllChildrenIterator&& aOther)
     : FlattenedChildIterator(Move(aOther)),
-      mOriginalContent(aOther.mOriginalContent),
       mAnonKids(Move(aOther.mAnonKids)), mAnonKidsIdx(aOther.mAnonKidsIdx),
       mFlags(aOther.mFlags), mPhase(aOther.mPhase)
 #ifdef DEBUG
@@ -203,11 +216,10 @@ public:
   // Seeks the given node in children of a parent element, starting from
   // the current iterator's position, and sets the iterator at the given child
   // node if it was found.
-  bool Seek(nsIContent* aChildToFind);
+  bool Seek(const nsIContent* aChildToFind);
 
   nsIContent* GetNextChild();
   nsIContent* GetPreviousChild();
-  const nsIContent* Parent() const { return mOriginalContent; }
 
   enum IteratorPhase
   {
@@ -225,8 +237,6 @@ private:
   void AppendNativeAnonymousChildren();
   void AppendNativeAnonymousChildrenFromFrame(nsIFrame* aFrame);
 
-  const nsIContent* mOriginalContent;
-
   // mAnonKids is an array of native anonymous children, mAnonKidsIdx is index
   // in the array. If mAnonKidsIdx < mAnonKids.Length() and mPhase is
   // eAtAnonKids then the iterator points at a child at mAnonKidsIdx index. If