Return error and exit from loop when there is error in compare bitmap test

This patch returns error and exit from loop when there is error in
comparing bitmap test.

Bug: skia:None
Change-Id: If7fe9d8cf6b936bf1fb84de69e73c453a6c253de
Reviewed-on: https://skia-review.googlesource.com/57600
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
1 file changed