Remove WebGL CHROMIUM image fallback logic.

A failure to allocate a CHROMIUM image should be treated the same as a failure
in texImage2D. This removes some unnecessary, poorly tested logic from WebGL.

BUG=581777

Review-Url: https://codereview.chromium.org/2021443003
Cr-Commit-Position: refs/heads/master@{#396982}
2 files changed