Create special surfaces according to original device (not always in N32)

src/core/SkImageFilter.cpp

Index: src/core/SkImageFilter.cpp
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index 64b62759e2c8b83dfd1ba0d61d161a61008b92bd..5fe471dc629f77e3025898185b695518f3fb1c25 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -347,8 +347,7 @@ bool SkImageFilter::applyCropRect(const Context& ctx, const SkIRect& srcBounds,
 static sk_sp<SkSpecialImage> pad_image(SkSpecialImage* src,
                                        int newWidth, int newHeight, int offX, int offY) {
 
-    SkImageInfo info = SkImageInfo::MakeN32Premul(newWidth, newHeight);
-    sk_sp<SkSpecialSurface> surf(src->makeSurface(info));
+    sk_sp<SkSpecialSurface> surf(src->makeSurface(SkIRect::MakeWH(newWidth, newHeight)));
     if (!surf) {
         return nullptr;
     }