Fix asserts for npot tiling in gl.

Change-Id: Iadbb0f85f929bf846f5ba03809b298b1d9d03786
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/329172
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
2 files changed