[Slimming Paint] Implement deferred SVG filters

Source/core/rendering/svg/RenderSVGResourceFilter.h

Index: Source/core/rendering/svg/RenderSVGResourceFilter.h
diff --git a/Source/core/rendering/svg/RenderSVGResourceFilter.h b/Source/core/rendering/svg/RenderSVGResourceFilter.h
index ff92d2dfd31f50f4dd01361447d3b97b61335249..bcbc79f0856aabf22a10adac9d5f30218f067c03 100644
--- a/Source/core/rendering/svg/RenderSVGResourceFilter.h
+++ b/Source/core/rendering/svg/RenderSVGResourceFilter.h
@@ -31,6 +31,8 @@
 
 namespace blink {
 
+class DisplayItemList;
+
 class FilterData final : public NoBaseWillBeGarbageCollected<FilterData> {
     WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED;
 public:
@@ -70,7 +72,9 @@ public:
     virtual void removeClientFromCache(RenderObject*, bool markForInvalidation = true) override;
 
     bool prepareEffect(RenderObject*, GraphicsContext*);
-    void finishEffect(RenderObject*, GraphicsContext*);
+    // FinishEffect takes a second context that contains the filtered content which will be
+    // drawn into the first context.
+    void finishEffect(RenderObject*, GraphicsContext*, GraphicsContext*);

[chrishtr, 2015/01/24 00:02:02]

Add names to these two graphics contexts, way too confusing otherwise. Is there
a way to avoid passing two contexts to the same method?

[pdr., 2015/01/24 01:13:36]

Done: used "primaryContext" and "contentContext".

 
     FloatRect resourceBoundingBox(const RenderObject*);