This migrates to the new generation style used in GLES2.

BUG=angleproject:1309

Change-Id: I43e9d33a0d7c5b1786452895855ff2bfbf82f139
Reviewed-on: https://chromium-review.googlesource.com/638311Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>