Implement SVG masking with slimming paint

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/layout/ClipPathOperation.h"
 #include "core/layout/FilterEffectRenderer.h"
@@ skipping 198 matching lines @@
     // Blending operations must be performed only with the nearest ancestor stacking context.
     // Note that there is no need to composite if we're painting the root.
     // FIXME: this should be unified further into Layer::paintsWithTransparency().
     bool shouldCompositeForBlendMode = (!m_renderLayer.renderer()->isDocumentElement() || m_renderLayer.renderer()->isSVGRoot()) && m_renderLayer.stackingNode()->isStackingContext() && m_renderLayer.hasNonIsolatedDescendantWithBlendMode();
     if (shouldCompositeForBlendMode || m_renderLayer.paintsWithTransparency(paintingInfo.paintBehavior)) {
         clipRecorder = adoptPtr(new LayerClipRecorder(m_renderLayer.renderer(), context, DisplayItem::TransparencyClip,
             m_renderLayer.paintingExtent(paintingInfo.rootLayer, paintingInfo.paintDirtyRect, paintingInfo.subPixelAccumulation, paintingInfo.paintBehavior),
             &paintingInfo, LayoutPoint(), paintFlags));
 
         compositingRecorder = adoptPtr(new CompositingRecorder(context, m_renderLayer.renderer()->displayItemClient(),
-            context->compositeOperationDeprecated(), m_renderLayer.renderer()->style()->blendMode(), m_renderLayer.renderer()->opacity()));
+            WebCoreCompositeToSkiaComposite(context->compositeOperationDeprecated(), m_renderLayer.renderer()->style()->blendMode()),
+            m_renderLayer.renderer()->opacity()));
     }
 
     LayerPaintingInfo localPaintingInfo(paintingInfo);
 
     LayerFragments layerFragments;
     if (shouldPaintContent || shouldPaintOutline || isPaintingOverlayScrollbars) {
         // Collect the fragments. This will compute the clip rectangles and paint offsets for each layer fragment.
         ClipRectsCacheSlot cacheSlot = (paintFlags & PaintLayerUncachedClipRects) ? UncachedClipRects : PaintingClipRects;
         ShouldRespectOverflowClip respectOverflowClip = shouldRespectOverflowClip(paintFlags, m_renderLayer.renderer());
         if (fragmentPolicy == ForceSingleFragment)
@@ skipping 477 matching lines @@
     if (!m_renderLayer.containsDirtyOverlayScrollbars())
         return;
 
     LayerPaintingInfo paintingInfo(&m_renderLayer, enclosingIntRect(damageRect), paintBehavior, LayoutSize(), paintingRoot);
     paintLayer(context, paintingInfo, PaintLayerPaintingOverlayScrollbars);
 
     m_renderLayer.setContainsDirtyOverlayScrollbars(false);
 }
 
 } // namespace blink