Use separate-sigma version of SkDropShadowImageFilter::Create

Use the separate x/y sigma version of 
SkDropShadowImageFilter's Create() factory, so we can remove 
the single-param one from Skia.

R=danakj@chromium.org
BUG=

Review URL: https://codereview.chromium.org/397393002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284213 0039d316-1c4b-4281-b951-d872f2087c98

cc/output/render_surface_filters.cc

@@ -209,6 +209,7 @@ skia::RefPtr<SkImageFilter> RenderSurfaceFilters::BuildImageFilter(
             SkIntToScalar(op.drop_shadow_offset().x()),
             SkIntToScalar(op.drop_shadow_offset().y()),
             SkIntToScalar(op.amount()),
+            SkIntToScalar(op.amount()),
             op.drop_shadow_color(),
             image_filter.get()));
         break;