Previously they were listed as requiring ARB_color_buffer_float in all
cases even if the extension has been merged in Desktop GL 3.0. Make it
require Desktop GL 3.0 _or_ the extension. This fixes the PackUnpackTest
and BlendMinMaxTest on Mac

BUG=angleproject:891

Change-Id: I504d9ed3ed9f1d908964181a6c21b79f1faee9b1
Reviewed-on: https://chromium-review.googlesource.com/298862Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tryjob-Request: Corentin Wallez <cwallez@chromium.org>
Tryjob-Request: Jamie Madill <jmadill@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>