Fix color bug in SkRRectsGaussianEdgeShader

Due to the code at the end of emitCode this shader was darker than the SkGaussianEdgeShader on Android.

This CL also removes the unused "pad" parameter.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2344963002
NOTREECHECKS=true
TBR=bsalomon@google.com

Review-Url: https://codereview.chromium.org/2344963002
3 files changed