Revert "Revert "implemented mustImplementGSInvocationsWithLoop workaround in sksl""

This reverts commit 8ea60736aaa92cf3cf24705fb356e9e09e85b1fd.

Bug: skia:
Change-Id: If77035e03430b469c2682788610b33ae0aefbe1f
Reviewed-on: https://skia-review.googlesource.com/20053
Reviewed-by: Chris Dalton <csmartdalton@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
8 files changed