Have Frame::tree() return a reference

Source/core/testing/Internals.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 675 matching lines @@
     toHTMLInputElement(element)->selectColorInColorChooser(Color(colorValue));
 }
 
 Vector<String> Internals::formControlStateOfPreviousHistoryItem(ExceptionState& es)
 {
     HistoryItem* mainItem = frame()->loader()->history()->previousItem();
     if (!mainItem) {
         es.throwUninformativeAndGenericDOMException(InvalidAccessError);
         return Vector<String>();
     }
-    String uniqueName = frame()->tree()->uniqueName();
+    String uniqueName = frame()->tree().uniqueName();
     if (mainItem->target() != uniqueName && !mainItem->childItemWithTarget(uniqueName)) {
         es.throwUninformativeAndGenericDOMException(InvalidAccessError);
         return Vector<String>();
     }
     return mainItem->target() == uniqueName ? mainItem->documentState() : mainItem->childItemWithTarget(uniqueName)->documentState();
 }
 
 void Internals::setFormControlStateOfPreviousHistoryItem(const Vector<String>& state, ExceptionState& es)
 {
     HistoryItem* mainItem = frame()->loader()->history()->previousItem();
     if (!mainItem) {
         es.throwUninformativeAndGenericDOMException(InvalidAccessError);
         return;
     }
-    String uniqueName = frame()->tree()->uniqueName();
+    String uniqueName = frame()->tree().uniqueName();
     if (mainItem->target() == uniqueName)
         mainItem->setDocumentState(state);
     else if (HistoryItem* subItem = mainItem->childItemWithTarget(uniqueName))
         subItem->setDocumentState(state);
     else
         es.throwUninformativeAndGenericDOMException(InvalidAccessError);
 }
 
 void Internals::enableMockSpeechSynthesizer()
 {
@@ skipping 888 matching lines @@
     return document->frame()->spellChecker().selectionStartHasMarkerFor(DocumentMarker::Grammar, from, length);
 }
 
 unsigned Internals::numberOfScrollableAreas(Document* document, ExceptionState&)
 {
     unsigned count = 0;
     Frame* frame = document->frame();
     if (frame->view()->scrollableAreas())
         count += frame->view()->scrollableAreas()->size();
 
-    for (Frame* child = frame->tree()->firstChild(); child; child = child->tree()->nextSibling()) {
+    for (Frame* child = frame->tree().firstChild(); child; child = child->tree().nextSibling()) {
         if (child->view() && child->view()->scrollableAreas())
             count += child->view()->scrollableAreas()->size();
     }
 
     return count;
 }
 
 bool Internals::isPageBoxVisible(Document* document, int pageNumber, ExceptionState& es)
 {
     if (!document) {
@@ skipping 644 matching lines @@
         return false;
     sharedContext->extensions()->loseContextCHROMIUM(Extensions3D::GUILTY_CONTEXT_RESET_ARB, Extensions3D::INNOCENT_CONTEXT_RESET_ARB);
     // To prevent tests that call loseSharedGraphicsContext3D from being
     // flaky, we call finish so that the context is guaranteed to be lost
     // synchronously (i.e. before returning).
     sharedContext->finish();
     return true;
 }
 
 }