This will ensure that new methods (placed at the end) don't collide
with the context pointer when using a mismatched platform.

BUG=angleproject:1892

Change-Id: Ice6a3ccaf3cc2a1e36a04bc217386cf096612176
Reviewed-on: https://chromium-review.googlesource.com/672147Reviewed-by: Frank Henigman <fjhenigman@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>