Handle coverage for hairline lines with sub pixel lengths correctly on GPU

Bug: skia:
Change-Id: I96de605bef7f2bbbc9d326f5e525590524d81bc5
Reviewed-on: https://skia-review.googlesource.com/59084
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
1 file changed