Disable clipping on root scroller's ancestors.

third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp

 /*
  * Copyright (C) 2009 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 99 matching lines @@
 
 GraphicsLayer::GraphicsLayer(GraphicsLayerClient* client)
     : m_client(client)
     , m_backgroundColor(Color::transparent)
     , m_opacity(1)
     , m_blendMode(WebBlendModeNormal)
     , m_hasTransformOrigin(false)
     , m_contentsOpaque(false)
     , m_shouldFlattenTransform(true)
     , m_backfaceVisibility(true)
-    , m_masksToBounds(false)
     , m_drawsContent(false)
     , m_contentsVisible(true)
     , m_isRootForIsolatedGroup(false)
     , m_hasScrollParent(false)
     , m_hasClipParent(false)
     , m_painted(false)
     , m_isTrackingPaintInvalidations(client && client->isTrackingPaintInvalidations())
     , m_paintingPhase(GraphicsLayerPaintAllWithOverflowClip)
     , m_parent(0)
     , m_maskLayer(0)
@@ skipping 814 matching lines @@
 
     m_renderingContext3d = context;
     m_layer->layer()->setRenderingContext(context);
 
     if (m_contentsLayer)
         m_contentsLayer->setRenderingContext(m_renderingContext3d);
 }
 
 void GraphicsLayer::setMasksToBounds(bool masksToBounds)
 {
-    m_masksToBounds = masksToBounds;
-    m_layer->layer()->setMasksToBounds(m_masksToBounds);
+    m_layer->layer()->setMasksToBounds(masksToBounds);
 }
 
 void GraphicsLayer::setDrawsContent(bool drawsContent)
 {
     // Note carefully this early-exit is only correct because we also properly call
     // WebLayer::setDrawsContent whenever m_contentsLayer is set to a new layer in setupContentsLayer().
     if (drawsContent == m_drawsContent)
         return;
 
     m_drawsContent = drawsContent;
@@ skipping 379 matching lines @@
 {
     if (!layer) {
         fprintf(stderr, "Cannot showGraphicsLayerTree for (nil).\n");
         return;
     }
 
     String output = layer->layerTreeAsText(blink::LayerTreeIncludesDebugInfo);
     fprintf(stderr, "%s\n", output.utf8().data());
 }
 #endif