Fix bounds computation of all 0-input filters.

src/core/SkImageFilter.cpp

Index: src/core/SkImageFilter.cpp
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index bba5ec0c7408c57b6235b0727b91d35c611249df..8f49a06c1511e116b9caaa65fbda07b493f4ce00 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -342,7 +342,8 @@ bool SkImageFilter::applyCropRect(const Context& ctx, Proxy* proxy, const SkBitm
 bool SkImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
                                    SkIRect* dst) const {
     if (fInputCount < 1) {
-        return false;
+        *dst = src;
+        return true;
     }
 
     SkIRect bounds;