Implement a computeFastBounds() traversal for SkImageFilter. This allows for correct culling of pri…

src/core/SkPaint.cpp

Index: src/core/SkPaint.cpp
diff --git a/src/core/SkPaint.cpp b/src/core/SkPaint.cpp
index f576015ba0f96c7af1fbea0544447a860e71590b..cc6d7ba1b3d792acc0f00b2f5d04dd224e086b0d 100644
--- a/src/core/SkPaint.cpp
+++ b/src/core/SkPaint.cpp
@@ -2288,6 +2288,10 @@ const SkRect& SkPaint::doComputeFastBounds(const SkRect& origSrc,
         this->getMaskFilter()->computeFastBounds(*storage, storage);
     }
 
+    if (this->getImageFilter()) {
+        this->getImageFilter()->computeFastBounds(*storage, storage);
+    }
+
     return *storage;
 }