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

third_party/WebKit/Source/core/testing/Internals.idl

 /*
  * 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 169 matching lines @@
     // The values of these constants must be kept in sync with the values of LayerTreeFlags in GraphicsLayerClient.h.
     const unsigned short LAYER_TREE_INCLUDES_DEBUG_INFO = 1;
     const unsigned short LAYER_TREE_INCLUDES_PAINT_INVALIDATIONS = 2;
     const unsigned short LAYER_TREE_INCLUDES_PAINTING_PHASES = 4;
     const unsigned short LAYER_TREE_INCLUDES_ROOT_LAYER = 8;
     const unsigned short LAYER_TREE_INCLUDES_CLIP_AND_SCROLL_PARENTS = 16;
     const unsigned short LAYER_TREE_INCLUDES_COMPOSITING_REASONS = 32;
     [RaisesException] DOMString layerTreeAsText(Document document, optional unsigned short flags);
     [RaisesException] DOMString elementLayerTreeAsText(Element element, optional unsigned short flags);
 
+    boolean isStackingContext(Element element);
+
     [RaisesException] boolean scrollsWithRespectTo(Element element1, Element element2);
 
     DOMString scrollingStateTreeAsText(Document document);
     [RaisesException] DOMString mainThreadScrollingReasons(Document document);
     [RaisesException] ClientRectList nonFastScrollableRects(Document document);
 
     void evictAllResources();
 
     unsigned long numberOfLiveNodes();
     unsigned long numberOfLiveDocuments();
@@ skipping 145 matching lines @@
 
     void setMediaElementNetworkState(HTMLMediaElement element, long state);
 
     // TODO(liberato): remove once autoplay gesture override experiment concludes.
     void triggerAutoplayViewportCheck(HTMLMediaElement mediaElement);
 
     DOMString getScrollAnimationState(Node node);
 
     DOMString getProgrammaticScrollAnimationState(Node node);
 };