bug 1016545 - Provide an iterator that iterates over all children of an element r=bz

accessible/base/TreeWalker.cpp

@@ -9,6 +9,7 @@
 #include "nsAccessibilityService.h"
 #include "DocAccessible.h"
 
+#include "mozilla/dom/ChildIterator.h"
 #include "mozilla/dom/Element.h"
 
 using namespace mozilla::a11y;
@@ -22,13 +23,12 @@ namespace a11y {
 
 struct WalkState
 {
-  WalkState(nsIContent *aContent) :
-    content(aContent), childIdx(0), prevState(nullptr) {}
+  WalkState(nsIContent *aContent, uint32_t aFilter) :
+    content(aContent), prevState(nullptr), iter(aContent, aFilter) {}
 
   nsCOMPtr<nsIContent> content;
-  nsCOMPtr<nsINodeList> childList;
-  uint32_t childIdx;
   WalkState *prevState;
+  dom::AllChildrenIterator iter;
 };
 
 } // namespace a11y
@@ -45,14 +45,13 @@ TreeWalker::
 {
   NS_ASSERTION(aContent, "No node for the accessible tree walker!");
 
-  if (aContent)
-    mState = new WalkState(aContent);
-
   mChildFilter = mContext->CanHaveAnonChildren() ?
     nsIContent::eAllChildren : nsIContent::eAllButXBL;
-
   mChildFilter |= nsIContent::eSkipPlaceholderContent;
 
+  if (aContent)
+    mState = new WalkState(aContent, mChildFilter);
+
   MOZ_COUNT_CTOR(TreeWalker);
 }
 
@@ -74,17 +73,7 @@ TreeWalker::NextChildInternal(bool aNoWalkUp)
   if (!mState || !mState->content)
     return nullptr;
 
-  if (!mState->childList)
-    mState->childList = mState->content->GetChildren(mChildFilter);
-
-  uint32_t length = 0;
-  if (mState->childList)
-    mState->childList->GetLength(&length);
-
-  while (mState->childIdx < length) {
-    nsIContent* childNode = mState->childList->Item(mState->childIdx);
-    mState->childIdx++;
-
+  while (nsIContent* childNode = mState->iter.GetNextChild()) {
     bool isSubtreeHidden = false;
     Accessible* accessible = mFlags & eWalkCache ?
       mDoc->GetAccessible(childNode) :
@@ -95,7 +84,7 @@ TreeWalker::NextChildInternal(bool aNoWalkUp)
       return accessible;
 
     // Walk down into subtree to find accessibles.
-    if (!isSubtreeHidden) {
+    if (!isSubtreeHidden && childNode->IsElement()) {
       PushState(childNode);
       accessible = NextChildInternal(true);
       if (accessible)
@@ -123,14 +112,7 @@ TreeWalker::NextChildInternal(bool aNoWalkUp)
       return nullptr;
 
     PushState(parentNode->AsElement());
-    mState->childList = mState->content->GetChildren(mChildFilter);
-    length = 0;
-    if (mState->childList)
-      mState->childList->GetLength(&length);
-
-    while (mState->childIdx < length) {
-      nsIContent* childNode = mState->childList->Item(mState->childIdx);
-      mState->childIdx++;
+    while (nsIContent* childNode = mState->iter.GetNextChild()) {
       if (childNode == anchorNode)
         return NextChildInternal(false);
     }
@@ -153,7 +135,7 @@ TreeWalker::PopState()
 void
 TreeWalker::PushState(nsIContent* aContent)
 {
-  WalkState* nextToLastState = new WalkState(aContent);
+  WalkState* nextToLastState = new WalkState(aContent, mChildFilter);
   nextToLastState->prevState = mState;
   mState = nextToLastState;
 }

content/base/src/ChildIterator.cpp

@@ -10,6 +10,8 @@
 #include "mozilla/dom/HTMLContentElement.h"
 #include "mozilla/dom/HTMLShadowElement.h"
 #include "mozilla/dom/ShadowRoot.h"
+#include "nsIAnonymousContentCreator.h"
+#include "nsIFrame.h"
 
 namespace mozilla {
 namespace dom {
@@ -154,11 +156,15 @@ ExplicitChildIterator::GetNextChild()
   return mChild;
 }
 
-FlattenedChildIterator::FlattenedChildIterator(nsIContent* aParent)
-  : ExplicitChildIterator(aParent), mXBLInvolved(false)
+void
+FlattenedChildIterator::Init(bool aIgnoreXBL)
 {
+  if (aIgnoreXBL) {
+    return;
+  }
+
   nsXBLBinding* binding =
-    aParent->OwnerDoc()->BindingManager()->GetBindingWithContent(aParent);
+    mParent->OwnerDoc()->BindingManager()->GetBindingWithContent(mParent);
 
   if (binding) {
     nsIContent* anon = binding->GetAnonymousContent();
@@ -171,8 +177,8 @@ FlattenedChildIterator::FlattenedChildIterator(nsIContent* aParent)
   // We set mXBLInvolved to true if either:
   // - The node we're iterating has a binding with content attached to it.
   // - The node is generated XBL content and has an <xbl:children> child.
-  if (!mXBLInvolved && aParent->GetBindingParent()) {
-    for (nsIContent* child = aParent->GetFirstChild();
+  if (!mXBLInvolved && mParent->GetBindingParent()) {
+    for (nsIContent* child = mParent->GetFirstChild();
          child;
          child = child->GetNextSibling()) {
       if (child->NodeInfo()->Equals(nsGkAtoms::children, kNameSpaceID_XBL)) {
@@ -281,5 +287,63 @@ ExplicitChildIterator::GetPreviousChild()
   return mChild;
 }
 
+nsIContent*
+AllChildrenIterator::GetNextChild()
+{
+  if (mPhase == eNeedBeforeKid) {
+    mPhase = eNeedExplicitKids;
+    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
+    if (frame) {
+      nsIFrame* beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
+      if (beforeFrame) {
+        return beforeFrame->GetContent();
+      }
+    }
+  }
+
+  if (mPhase == eNeedExplicitKids) {
+    nsIContent* kid = ExplicitChildIterator::GetNextChild();
+    if (kid) {
+      return kid;
+    }
+
+    mPhase = eNeedAnonKids;
+  }
+
+  if (mPhase == eNeedAnonKids) {
+    if (mAnonKids.IsEmpty()) {
+      nsIAnonymousContentCreator* ac =
+        do_QueryFrame(mOriginalContent->GetPrimaryFrame());
+      if (ac) {
+        ac->AppendAnonymousContentTo(mAnonKids, mFlags);
+      }
+    }
+
+    if (!mAnonKids.IsEmpty()) {
+      nsIContent* nextKid = mAnonKids[0];
+      mAnonKids.RemoveElementAt(0);
+      if (mAnonKids.IsEmpty()) {
+        mPhase = eNeedAfterKid;
+      }
+
+      return nextKid;
+    }
+
+    mPhase = eNeedAfterKid;
+  }
+
+  if (mPhase == eNeedAfterKid) {
+    mPhase = eDone;
+    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
+    if (frame) {
+      nsIFrame* afterFrame = nsLayoutUtils::GetAfterFrame(frame);
+      if (afterFrame) {
+        return afterFrame->GetContent();
+      }
+    }
+  }
+
+  return nullptr;
+}
 } // namespace dom
 } // namespace mozilla

content/base/src/ChildIterator.h

@@ -7,6 +7,8 @@
 #ifndef ChildIterator_h
 #define ChildIterator_h
 
+#include "nsIContent.h"
+
 /**
  * Iterates over the children on a node. If a child is an insertion point,
  * iterates over the children inserted there instead, or the default content
@@ -107,16 +109,73 @@ protected:
 class FlattenedChildIterator : public ExplicitChildIterator
 {
 public:
-  FlattenedChildIterator(nsIContent* aParent);
+  FlattenedChildIterator(nsIContent* aParent)
+    : ExplicitChildIterator(aParent), mXBLInvolved(false)
+  {
+    Init(false);
+  }
 
   bool XBLInvolved() { return mXBLInvolved; }
 
-private:
+protected:
+  /**
+   * This constructor is a hack to help AllChildrenIterator which sometimes
+   * doesn't want to consider XBL.
+   */
+  FlattenedChildIterator(nsIContent* aParent, bool aIgnoreXBL)
+  : ExplicitChildIterator(aParent), mXBLInvolved(false)
+  {
+    Init(aIgnoreXBL);
+  }
+
+  void Init(bool aIgnoreXBL);
+
   // For certain optimizations, nsCSSFrameConstructor needs to know if the
   // child list of the element that we're iterating matches its .childNodes.
   bool mXBLInvolved;
 };
 
+/**
+ * AllChildrenIterator returns the children of a element including before /
+ * after content and optionally XBL children.  It assumes that no mutation of
+ * the DOM or frame tree takes place during iteration, and will break horribly
+ * if that is not true.
+ */
+class AllChildrenIterator : private FlattenedChildIterator
+{
+public:
+  AllChildrenIterator(nsIContent* aNode, uint32_t aFlags) :
+    FlattenedChildIterator(aNode, (aFlags & nsIContent::eAllButXBL)),
+    mOriginalContent(aNode), mFlags(aFlags),
+    mPhase(eNeedBeforeKid) {}
+
+#ifdef DEBUG
+  ~AllChildrenIterator() { MOZ_ASSERT(!mMutationGuard.Mutated(0)); }
+#endif
+
+  nsIContent* GetNextChild();
+
+private:
+  enum IteratorPhase
+  {
+    eNeedBeforeKid,
+    eNeedExplicitKids,
+    eNeedAnonKids,
+    eNeedAfterKid,
+    eDone
+  };
+
+  nsIContent* mOriginalContent;
+  nsTArray<nsIContent*> mAnonKids;
+  uint32_t mFlags;
+  IteratorPhase mPhase;
+#ifdef DEBUG
+  // XXX we should really assert there are no frame tree changes as well, but
+  // there's no easy way to do that.
+  nsMutationGuard mMutationGuard;
+#endif
+};
+
 } // namespace dom
 } // namespace mozilla
 

content/base/src/FragmentOrElement.cpp

@@ -661,48 +661,9 @@ already_AddRefed<nsINodeList>
 FragmentOrElement::GetChildren(uint32_t aFilter)
 {
   nsRefPtr<nsSimpleContentList> list = new nsSimpleContentList(this);
-  if (!list) {
-    return nullptr;
-  }
-
-  nsIFrame *frame = GetPrimaryFrame();
-
-  // Append :before generated content.
-  if (frame) {
-    nsIFrame *beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
-    if (beforeFrame) {
-      list->AppendElement(beforeFrame->GetContent());
-    }
-  }
-
-  // If XBL is bound to this node then append XBL anonymous content including
-  // explict content altered by insertion point if we were requested for XBL
-  // anonymous content, otherwise append explicit content with respect to
-  // insertion point if any.
-  if (!(aFilter & eAllButXBL)) {
-    FlattenedChildIterator iter(this);
-    for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
-      list->AppendElement(child);
-    }
-  } else {
-    ExplicitChildIterator iter(this);
-    for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
-      list->AppendElement(child);
-    }
-  }
-
-  if (frame) {
-    // Append native anonymous content to the end.
-    nsIAnonymousContentCreator* creator = do_QueryFrame(frame);
-    if (creator) {
-      creator->AppendAnonymousContentTo(*list, aFilter);
-    }
-
-    // Append :after generated content.
-    nsIFrame *afterFrame = nsLayoutUtils::GetAfterFrame(frame);
-    if (afterFrame) {
-      list->AppendElement(afterFrame->GetContent());
-    }
+  AllChildrenIterator iter(this, aFilter);
+  while (nsIContent* kid = iter.GetNextChild()) {
+    list->AppendElement(kid);
   }
 
   return list.forget();

content/base/src/moz.build

@@ -61,6 +61,7 @@ EXPORTS.mozilla += [
 
 EXPORTS.mozilla.dom += [
     'Attr.h',
+    'ChildIterator.h',
     'Comment.h',
     'DocumentFragment.h',
     'DocumentType.h',

layout/forms/nsColorControlFrame.cpp

@@ -83,10 +83,12 @@ nsColorControlFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsColorControlFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsColorControlFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                               uint32_t aFilter)
 {
-  aElements.MaybeAppendElement(mColorContent);
+  if (mColorContent) {
+    aElements.AppendElement(mColorContent);
+  }
 }
 
 nsresult

layout/forms/nsColorControlFrame.h

@@ -37,7 +37,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
 
   // nsIFrame

layout/forms/nsComboboxControlFrame.cpp

@@ -1184,11 +1184,16 @@ nsComboboxControlFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsComboboxControlFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsComboboxControlFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                                  uint32_t aFilter)
 {
-  aElements.MaybeAppendElement(mDisplayContent);
-  aElements.MaybeAppendElement(mButtonContent);
+  if (mDisplayContent) {
+    aElements.AppendElement(mDisplayContent);
+  }
+
+  if (mButtonContent) {
+    aElements.AppendElement(mButtonContent);
+  }
 }
 
 // XXXbz this is a for-now hack.  Now that display:inline-block works,

layout/forms/nsComboboxControlFrame.h

@@ -59,7 +59,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
   virtual nsIFrame* CreateFrameFor(nsIContent* aContent) MOZ_OVERRIDE;
 

layout/forms/nsFileControlFrame.cpp

@@ -150,11 +150,16 @@ nsFileControlFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsFileControlFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsFileControlFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                              uint32_t aFilter)
 {
-  aElements.MaybeAppendElement(mBrowse);
-  aElements.MaybeAppendElement(mTextContent);
+  if (mBrowse) {
+    aElements.AppendElement(mBrowse);
+  }
+
+  if (mTextContent) {
+    aElements.AppendElement(mTextContent);
+  }
 }
 
 NS_QUERYFRAME_HEAD(nsFileControlFrame)

layout/forms/nsFileControlFrame.h

@@ -57,7 +57,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
 
 #ifdef ACCESSIBILITY

layout/forms/nsGfxButtonControlFrame.cpp

@@ -69,10 +69,12 @@ nsGfxButtonControlFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements
 }
 
 void
-nsGfxButtonControlFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsGfxButtonControlFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                                   uint32_t aFilter)
 {
-  aElements.MaybeAppendElement(mTextContent);
+  if (mTextContent) {
+    aElements.AppendElement(mTextContent);
+  }
 }
 
 // Create the text content used as label for the button.

layout/forms/nsGfxButtonControlFrame.h

@@ -40,7 +40,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
   virtual nsIFrame* CreateFrameFor(nsIContent* aContent) MOZ_OVERRIDE;
 

layout/forms/nsMeterFrame.cpp

@@ -79,10 +79,12 @@ nsMeterFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsMeterFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsMeterFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                        uint32_t aFilter)
 {
-  aElements.MaybeAppendElement(mBarDiv);
+  if (mBarDiv) {
+    aElements.AppendElement(mBarDiv);
+  }
 }
 
 NS_QUERYFRAME_HEAD(nsMeterFrame)

layout/forms/nsMeterFrame.h

@@ -42,7 +42,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
 
   virtual nsresult AttributeChanged(int32_t  aNameSpaceID,

layout/forms/nsNumberControlFrame.cpp

@@ -676,11 +676,13 @@ nsNumberControlFrame::ShouldUseNativeStyleForSpinner() const
 }
 
 void
-nsNumberControlFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsNumberControlFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                                uint32_t aFilter)
 {
   // Only one direct anonymous child:
-  aElements.MaybeAppendElement(mOuterWrapper);
+  if (mOuterWrapper) {
+    aElements.AppendElement(mOuterWrapper);
+  }
 }
 
 void

layout/forms/nsNumberControlFrame.h

@@ -68,7 +68,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
 
 #ifdef DEBUG_FRAME_DUMP

layout/forms/nsProgressFrame.cpp

@@ -76,10 +76,12 @@ nsProgressFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsProgressFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsProgressFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                           uint32_t aFilter)
 {
-  aElements.MaybeAppendElement(mBarDiv);
+  if (mBarDiv) {
+    aElements.AppendElement(mBarDiv);
+  }
 }
 
 NS_QUERYFRAME_HEAD(nsProgressFrame)

layout/forms/nsProgressFrame.h

@@ -47,7 +47,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
 
   virtual nsresult AttributeChanged(int32_t  aNameSpaceID,

layout/forms/nsRangeFrame.cpp

@@ -154,12 +154,20 @@ nsRangeFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsRangeFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsRangeFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                        uint32_t aFilter)
 {
-  aElements.MaybeAppendElement(mTrackDiv);
-  aElements.MaybeAppendElement(mProgressDiv);
-  aElements.MaybeAppendElement(mThumbDiv);
+  if (mTrackDiv) {
+    aElements.AppendElement(mTrackDiv);
+  }
+
+  if (mProgressDiv) {
+    aElements.AppendElement(mProgressDiv);
+  }
+
+  if (mThumbDiv) {
+    aElements.AppendElement(mThumbDiv);
+  }
 }
 
 class nsDisplayRangeFocusRing : public nsDisplayItem

layout/forms/nsRangeFrame.h

@@ -64,7 +64,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
 
   virtual nsresult AttributeChanged(int32_t  aNameSpaceID,

layout/forms/nsTextControlFrame.cpp

@@ -394,15 +394,20 @@ nsTextControlFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsTextControlFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsTextControlFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                              uint32_t aFilter)
 {
   nsCOMPtr<nsITextControlElement> txtCtrl = do_QueryInterface(GetContent());
   NS_ASSERTION(txtCtrl, "Content not a text control element");
 
-  aElements.MaybeAppendElement(txtCtrl->GetRootEditorNode());
-  if (!(aFilter & nsIContent::eSkipPlaceholderContent))
-    aElements.MaybeAppendElement(txtCtrl->GetPlaceholderNode());
+  nsIContent* root = txtCtrl->GetRootEditorNode();
+  if (root) {
+    aElements.AppendElement(root);
+  }
+
+  nsIContent* placeholder = txtCtrl->GetPlaceholderNode();
+  if (placeholder && !(aFilter & nsIContent::eSkipPlaceholderContent))
+    aElements.AppendElement(placeholder);
   
 }
 

layout/forms/nsTextControlFrame.h

@@ -82,7 +82,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
 
   virtual void SetInitialChildList(ChildListID     aListID,

layout/generic/nsCanvasFrame.cpp

@@ -114,11 +114,19 @@ nsCanvasFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsCanvasFrame::AppendAnonymousContentTo(nsBaseContentList& aElements, uint32_t aFilter)
+nsCanvasFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements, uint32_t aFilter)
 {
-  aElements.MaybeAppendElement(mTouchCaretElement);
-  aElements.MaybeAppendElement(mSelectionCaretsStartElement);
-  aElements.MaybeAppendElement(mSelectionCaretsEndElement);
+  if (mTouchCaretElement) {
+    aElements.AppendElement(mTouchCaretElement);
+  }
+
+  if (mSelectionCaretsStartElement) {
+    aElements.AppendElement(mSelectionCaretsStartElement);
+  }
+
+  if (mSelectionCaretsEndElement) {
+    aElements.AppendElement(mSelectionCaretsEndElement);
+  }
 }
 
 void

layout/generic/nsCanvasFrame.h

@@ -68,7 +68,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements, uint32_t aFilter) MOZ_OVERRIDE;
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements, uint32_t aFilter) MOZ_OVERRIDE;
 
   // Touch caret handle function
   mozilla::dom::Element* GetTouchCaretElement() const

layout/generic/nsGfxScrollFrame.cpp

@@ -104,7 +104,7 @@ nsHTMLScrollFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsHTMLScrollFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsHTMLScrollFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                             uint32_t aFilter)
 {
   mHelper.AppendAnonymousContentTo(aElements, aFilter);
@@ -1048,7 +1048,7 @@ nsXULScrollFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsXULScrollFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsXULScrollFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                            uint32_t aFilter)
 {
   mHelper.AppendAnonymousContentTo(aElements, aFilter);
@@ -3546,13 +3546,24 @@ ScrollFrameHelper::CreateAnonymousContent(
 }
 
 void
-ScrollFrameHelper::AppendAnonymousContentTo(nsBaseContentList& aElements,
+ScrollFrameHelper::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                                 uint32_t aFilter)
 {
-  aElements.MaybeAppendElement(mHScrollbarContent);
-  aElements.MaybeAppendElement(mVScrollbarContent);
-  aElements.MaybeAppendElement(mScrollCornerContent);
-  aElements.MaybeAppendElement(mResizerContent);
+  if (mHScrollbarContent) {
+    aElements.AppendElement(mHScrollbarContent);
+  }
+
+  if (mVScrollbarContent) {
+    aElements.AppendElement(mVScrollbarContent);
+  }
+
+  if (mScrollCornerContent) {
+    aElements.AppendElement(mScrollCornerContent);
+  }
+
+  if (mResizerContent) {
+    aElements.AppendElement(mResizerContent);
+  }
 }
 
 void

layout/generic/nsGfxScrollFrame.h

@@ -58,7 +58,7 @@ public:
 
   nsresult CreateAnonymousContent(
     nsTArray<nsIAnonymousContentCreator::ContentInfo>& aElements);
-  void AppendAnonymousContentTo(nsBaseContentList& aElements, uint32_t aFilter);
+  void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements, uint32_t aFilter);
   nsresult FireScrollPortEvent();
   void PostOverflowEvent();
   void Destroy();
@@ -544,7 +544,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
 
   // nsIScrollbarOwner
@@ -833,7 +833,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
 
   virtual nsSize GetMinSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE;

layout/generic/nsIAnonymousContentCreator.h

@@ -69,7 +69,7 @@ public:
    *
    * @see nsIContent::GetChildren for set of values used for filter.
    */
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) = 0;
 
   /**

layout/generic/nsVideoFrame.cpp

@@ -121,12 +121,20 @@ nsVideoFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsVideoFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsVideoFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                        uint32_t aFliter)
 {
-  aElements.MaybeAppendElement(mPosterImage);
-  aElements.MaybeAppendElement(mVideoControls);
-  aElements.MaybeAppendElement(mCaptionDiv);
+  if (mPosterImage) {
+    aElements.AppendElement(mPosterImage);
+  }
+
+  if (mVideoControls) {
+    aElements.AppendElement(mVideoControls);
+  }
+
+  if (mCaptionDiv) {
+    aElements.AppendElement(mCaptionDiv);
+  }
 }
 
 void

layout/generic/nsVideoFrame.h

@@ -76,7 +76,7 @@ public:
   }
   
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilters) MOZ_OVERRIDE;
 
   nsIContent* GetPosterImage() { return mPosterImage; }

layout/svg/nsSVGUseFrame.cpp

@@ -64,7 +64,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
 
 private:
@@ -243,10 +243,12 @@ nsSVGUseFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsSVGUseFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsSVGUseFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter)
 {
   SVGUseElement *use = static_cast<SVGUseElement*>(mContent);
   nsIContent* clone = use->GetAnonymousContent();
-  aElements.MaybeAppendElement(clone);
+  if (clone) {
+    aElements.AppendElement(clone);
+  }
 }

layout/xul/nsDocElementBoxFrame.cpp

@@ -43,7 +43,7 @@ public:
 
   // nsIAnonymousContentCreator
   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements) MOZ_OVERRIDE;
-  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+  virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) MOZ_OVERRIDE;
 
   virtual bool IsFrameOfType(uint32_t aFlags) const MOZ_OVERRIDE
@@ -123,11 +123,16 @@ nsDocElementBoxFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 }
 
 void
-nsDocElementBoxFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
+nsDocElementBoxFrame::AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                                uint32_t aFilter)
 {
-  aElements.MaybeAppendElement(mPopupgroupContent);
-  aElements.MaybeAppendElement(mTooltipContent);
+  if (mPopupgroupContent) {
+    aElements.AppendElement(mPopupgroupContent);
+  }
+
+  if (mTooltipContent) {
+    aElements.AppendElement(mTooltipContent);
+  }
 }
 
 NS_QUERYFRAME_HEAD(nsDocElementBoxFrame)