Implement -webkit-box-reflect as a filter.

third_party/WebKit/Source/core/paint/PaintLayer.h

Index: third_party/WebKit/Source/core/paint/PaintLayer.h
diff --git a/third_party/WebKit/Source/core/paint/PaintLayer.h b/third_party/WebKit/Source/core/paint/PaintLayer.h
index 26d5c2743437f147a4ff81c370372c8d32b93895..145c0dba7b795bbbfaff3923e30881ace94f0026 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.h
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.h
@@ -362,7 +362,7 @@ public:
 
     // If true, this layer's children are included in its bounds for overlap testing.
     // We can't rely on the children's positions if this layer has a filter that could have moved the children's pixels around.
-    bool overlapBoundsIncludeChildren() const { return hasFilter() && layoutObject()->style()->filter().hasFilterThatMovesPixels(); }
+    bool overlapBoundsIncludeChildren() const;
 
     // MaybeIncludeTransformForAncestorLayer means that a transform on |ancestorLayer| may be applied to the bounding box,
     // in particular if paintsWithTransform() is true.
@@ -404,6 +404,7 @@ public:
 
     void filterNeedsPaintInvalidation();
     bool hasFilter() const { return layoutObject()->hasFilter(); }
+    bool hasFilterInducingProperty() const { return layoutObject()->hasFilterInducingProperty(); }
 
     void* operator new(size_t);
     // Only safe to call from LayoutBoxModelObject::destroyLayer()
@@ -464,6 +465,7 @@ public:
     bool paintsWithFilters() const;
     bool paintsWithBackdropFilters() const;
     FilterEffect* lastFilterEffect() const;
+    bool hasFilterOutsets() const;
     FilterOutsets filterOutsets() const;
 
     PaintLayerFilterInfo* filterInfo() const { return hasFilterInfo() ? PaintLayerFilterInfo::filterInfoForLayer(this) : 0; }