Add the missing shift to the dy

BUG=chromium:668907

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=5266

Change-Id: I6d3e56ffc149fbeac6f7a2df740542abbf84dac8
Reviewed-on: https://skia-review.googlesource.com/5266
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Yuqian Li <liyuqian@google.com>
2 files changed