Fix abs intrinsic detection in GLSL backend.

We should detect intrinsics by enum, not by string matching. This was
missed when doing the initial conversion from strings to enums.

Change-Id: I87fb63274085d17d8c14e72667b95019edee25b3
Bug: skia:11961
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/410100
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
1 file changed