Remove unnecessary gl_FragCoord workaround

Bug: skia:
Change-Id: I04b6cbfe083c32a25205e04a4b15672d4b678a9c
Reviewed-on: https://skia-review.googlesource.com/c/174063
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
3 files changed