layout-tests: Add flag for including compositingReasons in layerTreeAsText().

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 151 matching lines @@
     readonly attribute unsigned long workerThreadCount;
 
     // Flags for layerTreeAsText.
     // The values of these constants must be kept in sync with the values of LayerTreeAsTextBehaviorFlags in GraphicsLayerClient.h.
     const unsigned short LAYER_TREE_INCLUDES_REPAINT_RECTS = 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_SCROLL_BLOCKS_ON = 32;
     const unsigned short LAYER_TREE_INCLUDES_PAINT_INVALIDATION_OBJECTS = 64;
+    const unsigned short LAYER_TREE_INCLUDES_COMPOSITING_REASONS = 128;
     [RaisesException, TypeChecking=Interface] DOMString layerTreeAsText(Document document, optional unsigned short flags);
     [RaisesException, TypeChecking=Interface] DOMString elementLayerTreeAsText(Element element, optional unsigned short flags);
 
     [RaisesException, TypeChecking=Interface] boolean scrollsWithRespectTo(Element element1, Element element2);
 
     [TypeChecking=Interface] DOMString scrollingStateTreeAsText(Document document);
     [RaisesException, TypeChecking=Interface] DOMString mainThreadScrollingReasons(Document document);
     [RaisesException, TypeChecking=Interface] ClientRectList nonFastScrollableRects(Document document);
 
     [TypeChecking=Interface] void garbageCollectDocumentResources(Document document);
@@ skipping 124 matching lines @@
 
     boolean isUseCounted(Document document, long useCounterId);
 
     iterable<long>;
 
     [Unscopeable] readonly attribute DOMString unscopeableAttribute;
     [Unscopeable] DOMString unscopeableMethod();
 
     ClientRectList focusRingRects(Element element);
 };