[sksl] Fix ModifiersDeclaration checks to include local_size_z

local_size_y was included in the guard twice and local_size_z was not.
This fixes that.

Change-Id: Ib0d10ead807e21ad6f8392ccff369ab430e9fff1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/735178
Commit-Queue: Arman Uguray <armansito@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
5 files changed