LinearGradientContext::shade4_clamp: fix div by 0

getScaleX() may return 0; move division using it after a
SkScalarNearlyZero check and closer to its first use.

Change-Id: Ie209d46dc101213e20e90486651ee17570425bb8
Reviewed-on: https://skia-review.googlesource.com/4643
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
2 files changed