We never used it internally, but the shaders used by Filament rely on
it. It doesn't exist in ES2 so this doesn't affect Runtime Effects.
Change-Id: Idb2afb15ff160b950ad02101bf6381a5d5c56468
Bug: skia:12635, skia:11209
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/470156
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
