This allows chromium to build with upstream headers that
include these extension. The old TEMP enums and structure
types are used until drivers have been updated to support
upstream header values.

Bug: chromium:1191605
Change-Id: I25d2991204ca34956298013138af8f48e0aaefaf
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2782765
Commit-Queue: David Reveman <reveman@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>