Enable proper testing of const arrays.

This test was generating invalid code in Metal
(http://review.skia.org/408356), but we didn't catch it because the code
wasn't actually being run.

Change-Id: I649034593a566f9e835b1cf7b0702c64952d31ef
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/408641
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
5 files changed