On OSX 10.8 with an Intel HD 3000 we were wrongly exposing ES3 when
texture swizzling was not available.

BUG=angleproject:891

Change-Id: If71acdc1943ab2f013dc80cd28eab130c32fb201
Reviewed-on: https://chromium-review.googlesource.com/303392Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tryjob-Request: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>