Enable shader validation with WebGL compatibility extension. The change configures shaders to be of a compatible spec upon creation. BUG=angleproject:1523 Change-Id: Id345d0b8f0abad8ed3c4fb3117d0fdfeab9fea53 Reviewed-on: https://chromium-review.googlesource.com/405778 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>