Updated workaround for Intel 6xxx clear to 0/1 bug

The previous workaround only handled the glClearColor(0,0,0,1) case,
it turns out we need to work around any glClearColor made up of entirely
0s and 1s.

R=bsalomon@google.com
Bug: 710443
Change-Id: I78a75559fc11811ad9a218436231354d66d2ad51
Reviewed-on: https://skia-review.googlesource.com/17327
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Eric Karl <ericrk@chromium.org>
3 files changed