Check negative width before blitAntiRect

Since we decrease the width when clipped, it might be negative.

Bug: skia:7858
Change-Id: I348bd07d917905a55bec1a4b4e0915c6528fe6b1
Reviewed-on: https://skia-review.googlesource.com/123927
Auto-Submit: Yuqian Li <liyuqian@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Yuqian Li <liyuqian@google.com>
1 file changed