Adds filter support for offscreen canvas

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

Index: third_party/WebKit/Source/core/paint/FilterEffectBuilder.h
diff --git a/third_party/WebKit/Source/core/paint/FilterEffectBuilder.h b/third_party/WebKit/Source/core/paint/FilterEffectBuilder.h
index 3d7d597a2dca88062ebf40119696346d637db162..02f06ea87c6714185b4dcb89d8061562cf1e8066 100644
--- a/third_party/WebKit/Source/core/paint/FilterEffectBuilder.h
+++ b/third_party/WebKit/Source/core/paint/FilterEffectBuilder.h
@@ -49,6 +49,10 @@ class CORE_EXPORT FilterEffectBuilder final {
   STACK_ALLOCATED();
 
  public:
+  FilterEffectBuilder(const FloatRect& zoomedReferenceBox,
+                      float zoom,
+                      const SkPaint* fillPaint = nullptr,
+                      const SkPaint* strokePaint = nullptr);
   FilterEffectBuilder(Node*,
                       const FloatRect& zoomedReferenceBox,
                       float zoom,