Re-add assert for mip maps.

Bug: skia:
Change-Id: Iec418be2a02b046aa528df4b019be6e98bcdf320
Reviewed-on: https://skia-review.googlesource.com/142802
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
1 file changed