compositor-worker: Force elements to grow a layer when a CompositorProxy is created.

Source/core/layout/LayoutBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. 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
@@ skipping 94 matching lines @@
     , m_maxPreferredLogicalWidth(-1)
 {
     setIsBox();
 }
 
 DeprecatedPaintLayerType LayoutBox::layerTypeRequired() const
 {
     // hasAutoZIndex only returns true if the element is positioned or a flex-item since
     // position:static elements that are not flex-items get their z-index coerced to auto.
     if (isPositioned() || createsGroup() || hasClipPath() || hasTransformRelatedProperty()
-        || hasHiddenBackface() || hasReflection() || style()->specifiesColumns()
+        || style()->hasCompositorProxy() || hasHiddenBackface() || hasReflection() || style()->specifiesColumns()
         || !style()->hasAutoZIndex() || style()->shouldCompositeForCurrentAnimations())
         return NormalDeprecatedPaintLayer;
 
     // Ensure that explicit use of scroll-blocks-on creates a Layer (since we might need
     // it to be composited).
     if (style()->hasScrollBlocksOn()) {
         if (isDocumentElement()) {
             ASSERT(style()->scrollBlocksOn() == view()->style()->scrollBlocksOn());
             return NoDeprecatedPaintLayer;
         }
@@ skipping 4519 matching lines @@
     computedValues.m_margins.m_end = marginEnd();
 
     setLogicalTop(oldLogicalTop);
     setLogicalWidth(oldLogicalWidth);
     setLogicalLeft(oldLogicalLeft);
     setMarginLeft(oldMarginLeft);
     setMarginRight(oldMarginRight);
 }
 
 } // namespace blink