Fix filter bounds computation for SkOffsetImageFilter.

src/effects/SkOffsetImageFilter.cpp

Index: src/effects/SkOffsetImageFilter.cpp
diff --git a/src/effects/SkOffsetImageFilter.cpp b/src/effects/SkOffsetImageFilter.cpp
index ae35a4ca2f7875633cd3d40995ad97e328705e39..7680c62cfc948738b9f8e9dea124ef07666f50d7 100644
--- a/src/effects/SkOffsetImageFilter.cpp
+++ b/src/effects/SkOffsetImageFilter.cpp
@@ -84,6 +84,9 @@ bool SkOffsetImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm
     SkIRect bounds = src;
     bounds.offset(-SkScalarCeilToInt(vec.fX), -SkScalarCeilToInt(vec.fY));
     bounds.join(src);
+    if (getInput(0)) {
+        return getInput(0)->filterBounds(bounds, ctm, dst);
+    }
     *dst = bounds;
     return true;
 }