Remove the HasOwnBackingButPaintsIntoAncestor compositing state.

Source/core/paint/LayerPainter.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/paint/LayerPainter.h"
 
 #include "core/frame/Settings.h"
 #include "core/page/Page.h"
 #include "core/rendering/ClipPathOperation.h"
@@ skipping 484 matching lines @@
 static bool paintForFixedRootBackground(const RenderLayer* layer, PaintLayerFlags paintFlags)
 {
     return layer->renderer()->isDocumentElement() && (paintFlags & PaintLayerPaintingRootBackgroundOnly);
 }
 
 bool LayerPainter::shouldPaintLayerInSoftwareMode(const LayerPaintingInfo& paintingInfo, PaintLayerFlags paintFlags)
 {
     DisableCompositingQueryAsserts disabler;
 
     return m_renderLayer.compositingState() == NotComposited
-        || m_renderLayer.compositingState() == HasOwnBackingButPaintsIntoAncestor
         || (paintingInfo.paintBehavior & PaintBehaviorFlattenCompositingLayers)
         || ((paintFlags & PaintLayerPaintingReflection) && !m_renderLayer.has3DTransform())
         || paintForFixedRootBackground(&m_renderLayer, paintFlags);
 }
 
 static inline LayoutSize subPixelAccumulationIfNeeded(const LayoutSize& subPixelAccumulation, CompositingState compositingState)
 {
     // Only apply the sub-pixel accumulation if we don't paint into our own backing layer, otherwise the position
     // of the renderer already includes any sub-pixel offset.
     if (compositingState == PaintsIntoOwnBacking)
@@ skipping 359 matching lines @@
             clipRecorder = adoptPtr(new ClipRecorder(m_renderLayer.parent(), context, DisplayItem::ClipLayerFragmentParent, clipRect));
             // FIXME: why should we have to deal with rounded rect clips here at all?
             LayerPainter(*m_renderLayer.parent()).applyRoundedRectClips(paintingInfo, context, clipRect, paintFlags, *clipRecorder);
         }
 
         paintLayerByApplyingTransform(context, paintingInfo, paintFlags, fragment.paginationOffset);
     }
 }
 
 } // namespace blink