On ARM disable blend when src-over has src with alpha of 1.

Change-Id: Ibb8ed86b8753718dfd12a24ad9497f79093eea40
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/263200
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
9 files changed