Make SkImageFilter crop rects relative to the primitive origin, instead of relative to their parent

src/effects/SkPictureImageFilter.cpp

Index: src/effects/SkPictureImageFilter.cpp
diff --git a/src/effects/SkPictureImageFilter.cpp b/src/effects/SkPictureImageFilter.cpp
index 5b4af6548c02469946f109ef02636db27efaa970..bc3ed6a51f38e12acbb1840aedce471968301641 100644
--- a/src/effects/SkPictureImageFilter.cpp
+++ b/src/effects/SkPictureImageFilter.cpp
@@ -71,7 +71,7 @@ bool SkPictureImageFilter::onFilterImage(Proxy* proxy, const SkBitmap&, const Sk
     canvas.drawPicture(*fPicture);
 
     *result = device.get()->accessBitmap(false);
-    offset->fX += bounds.fLeft;
-    offset->fY += bounds.fTop;
+    offset->fX = bounds.fLeft;
+    offset->fY = bounds.fTop;
     return true;
 }