This should fix the buffer allocation crash manifesting on Windows 7
x64.

Bug: angleproject:3261
Bug: chromium:944454
Change-Id: I8a0713e1d1f18285f128c0cfb98b398c6a336a36
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1534461Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>