Add a workaround for platforms with broken geo shader invocations

BUG=skia:

Change-Id: I9105b65b522d9ffac5a90ca7126bfd4ae88f8069
Reviewed-on: https://skia-review.googlesource.com/8422
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
5 files changed