Avoid touching z-index in StyleAdjuster by using an isStackingContext flag instead

third_party/WebKit/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 1702 matching lines @@
     if (!layer
         || !layer->hasCompositedLayerMapping()
         || !layer->compositedLayerMapping()->mainGraphicsLayer()) {
         // Don't raise exception in these cases which may be normally used in tests.
         return String();
     }
 
     return layer->compositedLayerMapping()->mainGraphicsLayer()->layerTreeAsText(flags);
 }
 
+bool Internals::isStackingContext(Element* element) const
+{
+    return element->layoutObject()->style()->isStackingContext();
+}
+
 String Internals::scrollingStateTreeAsText(Document*) const
 {
     return String();
 }
 
 String Internals::mainThreadScrollingReasons(Document* document, ExceptionState& exceptionState) const
 {
     ASSERT(document);
     if (!document->frame()) {
         exceptionState.throwDOMException(InvalidAccessError, "The document provided is invalid.");
@@ skipping 831 matching lines @@
 }
 
 String Internals::getProgrammaticScrollAnimationState(Node* node) const
 {
     if (ScrollableArea* scrollableArea = scrollableAreaForNode(node))
         return scrollableArea->programmaticScrollAnimator().runStateAsText();
     return String();
 }
 
 } // namespace blink