Refactor uniform block binding Remove mUniformBlockBindings and move its bindings to mUniformBlocks. BUG=angleproject:1442 Change-Id: I62b4471990a44e626d2357c41cb914abc27cb18f Reviewed-on: https://chromium-review.googlesource.com/532834 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>