Image filters: optimize crop rect application

src/effects/SkMatrixConvolutionImageFilter.cpp

Index: src/effects/SkMatrixConvolutionImageFilter.cpp
diff --git a/src/effects/SkMatrixConvolutionImageFilter.cpp b/src/effects/SkMatrixConvolutionImageFilter.cpp
index c8b43bbfd0de8a34b8a232ec8bc5c296c79490f2..2a32fd5cdcebcfa9ac58e227a2af53c49104d419 100644
--- a/src/effects/SkMatrixConvolutionImageFilter.cpp
+++ b/src/effects/SkMatrixConvolutionImageFilter.cpp
@@ -337,10 +337,10 @@ SkIRect SkMatrixConvolutionImageFilter::onFilterNodeBounds(const SkIRect& src, c
     return dst;
 }
 
-bool SkMatrixConvolutionImageFilter::canComputeFastBounds() const {
+bool SkMatrixConvolutionImageFilter::affectsTransparentBlack() const {
     // Because the kernel is applied in device-space, we have no idea what
     // pixels it will affect in object-space.
-    return false;
+    return true;
 }
 
 #if SK_SUPPORT_GPU