Fix MatrixImageFilter computeFastBounds

src/effects/SkMatrixImageFilter.cpp

Index: src/effects/SkMatrixImageFilter.cpp
diff --git a/src/effects/SkMatrixImageFilter.cpp b/src/effects/SkMatrixImageFilter.cpp
index 919dff3994f3d822443c5601f47ed2a8dd6cd41f..f2c403f443aa450e64ec75108f390bf1b4a8cabe 100644
--- a/src/effects/SkMatrixImageFilter.cpp
+++ b/src/effects/SkMatrixImageFilter.cpp
@@ -98,11 +98,8 @@ void SkMatrixImageFilter::computeFastBounds(const SkRect& src, SkRect* dst) cons
     if (getInput(0)) {
         getInput(0)->computeFastBounds(src, &bounds);
     }
-    SkMatrix matrix;
-    matrix.setTranslate(-bounds.x(), -bounds.y());
-    matrix.postConcat(fTransform);
-    matrix.postTranslate(bounds.x(), bounds.y());
-    matrix.mapRect(dst, bounds);
+    fTransform.mapRect(dst, bounds);
+    dst->join(bounds);   // Work around for skia:3194

[Stephen White, 2014/12/08 17:20:51]

This really doesn't seem right to me, and we could come up with cases where
it'll fail. I think we really need the CTM here to do this correctly.

Granted, the original implementation wasn't correct either, but I'd rather get
us closer to correct than just paper over individual cases.

 }
 
 bool SkMatrixImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,