Delete the Layer Squashing runtime feature.

Source/core/rendering/compositing/RenderLayerCompositor.cpp

 /*
  * Copyright (C) 2009, 2010 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 136 matching lines @@
 
 void RenderLayerCompositor::updateAcceleratedCompositingSettings()
 {
     m_compositingReasonFinder.updateTriggers();
     m_hasAcceleratedCompositing = m_renderView.document().settings()->acceleratedCompositingEnabled();
     m_rootShouldAlwaysCompositeDirty = true;
     if (m_rootLayerAttachment != RootLayerUnattached)
         rootRenderLayer()->setNeedsCompositingInputsUpdate();
 }
 
-bool RenderLayerCompositor::layerSquashingEnabled() const
-{
-    if (!RuntimeEnabledFeatures::layerSquashingEnabled())
-        return false;
-    if (Settings* settings = m_renderView.document().settings())
-        return settings->layerSquashingEnabled();
-    return true;
-}
-
 bool RenderLayerCompositor::preferCompositingToLCDTextEnabled() const
 {
     return m_compositingReasonFinder.hasOverflowScrollTrigger();
 }
 
 static RenderVideo* findFullscreenVideoRenderer(Document& document)
 {
     // Recursively find the document that is in fullscreen.
     Element* fullscreenElement = Fullscreen::fullscreenElementFrom(document);
     Document* contentDocument = &document;
@@ skipping 1017 matching lines @@
     } else if (graphicsLayer == m_scrollLayer.get()) {
         name = "LocalFrame Scrolling Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink