Revert of Remove RenderLayer::collectFragments.

sky/engine/core/rendering/RenderLayer.h

Index: sky/engine/core/rendering/RenderLayer.h
diff --git a/sky/engine/core/rendering/RenderLayer.h b/sky/engine/core/rendering/RenderLayer.h
index ae02bf26d0ed04dcfb2878aa0db1a337caf07588..02c2ed800c2f67d11110fcc3fcf7fcc8c5807ced 100644
--- a/sky/engine/core/rendering/RenderLayer.h
+++ b/sky/engine/core/rendering/RenderLayer.h
@@ -464,6 +464,9 @@
 
     void paintChildren(unsigned childrenToVisit, GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags);
 
+    void collectFragments(LayerFragments&, const RenderLayer* rootLayer, const LayoutRect& dirtyRect,
+        ClipRectsCacheSlot, const LayoutPoint* offsetFromRoot = 0,
+        const LayoutSize& subPixelAccumulation = LayoutSize(), const LayoutRect* layerBoundingBox = 0);
     void updatePaintingInfoForFragments(LayerFragments&, const LayerPaintingInfo&, bool shouldPaintContent, const LayoutPoint* offsetFromRoot);
     void paintBackgroundForFragments(const LayerFragments&, GraphicsContext*, GraphicsContext* transparencyLayerContext,
         const LayoutRect& transparencyPaintDirtyRect, bool haveTransparency, const LayerPaintingInfo&, RenderObject* paintingRootForRenderer);
@@ -492,6 +495,7 @@
                             const LayoutPoint& translationOffset = LayoutPoint()) const;
 
     bool hitTestContents(const HitTestRequest&, HitTestResult&, const LayoutRect& layerBounds, const HitTestLocation&, HitTestFilter) const;
+    bool hitTestContentsForFragments(const LayerFragments&, const HitTestRequest&, HitTestResult&, const HitTestLocation&, HitTestFilter, bool& insideClipRect) const;
 
     bool childBackgroundIsKnownToBeOpaqueInRect(const LayoutRect&) const;