This is a hack to force an equivalent of eglSwapInterval(0) for perf
testing on the bots. This isn't quite the same as Immediate but
Immediate doesn't seem to be as widely available.

BUG=angleproject:1898

Change-Id: I3c5053e58969ba48f4f8595138e8fd38ea059bf6
Reviewed-on: https://chromium-review.googlesource.com/445798Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>