Implement will-change-based creation of layers, stacking contexts, and containing blocks

Source/core/rendering/RenderBoxModelObject.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 70 matching lines @@
 
     int pixelSnappedOffsetLeft() const { return roundToInt(offsetLeft()); }
     int pixelSnappedOffsetTop() const { return roundToInt(offsetTop()); }
     virtual int pixelSnappedOffsetWidth() const;
     virtual int pixelSnappedOffsetHeight() const;
 
     virtual void updateFromStyle() OVERRIDE;
 
     virtual LayerType layerTypeRequired() const OVERRIDE
     {
-        if (isRoot() || isPositioned() || createsGroup() || hasClipPath() || hasTransform() || hasHiddenBackface() || hasReflection() || style()->specifiesColumns())
+        if (isRoot() || isPositioned() || createsGroup() || hasClipPath() || hasTransform() || hasHiddenBackface() || hasReflection() || style()->specifiesColumns() || style()->hasWillChangeCompositingHint())
             return NormalLayer;
 
         return NoLayer;
     }
 
     // This will work on inlines to return the bounding box of all of the lines' border boxes.
     virtual IntRect borderBoundingBox() const = 0;
 
     // These return the CSS computed padding values.
     LayoutUnit computedCSSPaddingTop() const { return computedCSSPadding(style()->paddingTop()); }
@@ skipping 227 matching lines @@
     void drawBoxSideFromPath(GraphicsContext*, const LayoutRect&, const Path&, const class BorderEdge[],
                             float thickness, float drawThickness, BoxSide, const RenderStyle*,
                             Color, EBorderStyle, BackgroundBleedAvoidance, bool includeLogicalLeftEdge, bool includeLogicalRightEdge);
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderBoxModelObject, isBoxModelObject());
 
 } // namespace WebCore
 
 #endif // RenderBoxModelObject_h