We were rejecting npot textures for level 0, even though it is
valid in GLES 2 for non-mipped textures to have npot size.

BUG=381495

Change-Id: Iacc3ab50d6487ecba804fd8963aa0a2ada2f1cae
Reviewed-on: https://chromium-review.googlesource.com/205220Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Nicolas Capens <nicolascapens@chromium.org>