CMAA: Avoid DCHECK failure for unsupported internalformats

CMAA implementation replies on CopyTextureCHROMIUM extension which only
supports part of ES3 formats. Skip CMAA for those unsupported formats.

BUG=535198, 687180
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2697503002
Cr-Commit-Position: refs/heads/master@{#450920}
2 files changed