Always use the highest GL version available unless requested. BUG=angleproject:890 Change-Id: I76a1b1c455cb4be02b4b5c52153f5c87f33d426d Reviewed-on: https://chromium-review.googlesource.com/275008 Reviewed-by: Kenneth Russell <kbr@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>