This is useful for building the sample within Chromium rather than
in ANGLE's standalone build, which has other requirements like a
full Visual Studio installation.

BUG=angleproject:2095

Change-Id: I785d87ecb5166d8f640a5c8a5f321c3209017cc5
Reviewed-on: https://chromium-review.googlesource.com/553399Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>