This change is pure refactoring. It will help with fixing comma operator
return value qualifier bug.

BUG=angleproject:911
BUG=angleproject:1201

Change-Id: I481c337adbaf789cc959c8a1106f99ad7275e1e5
Reviewed-on: https://chromium-review.googlesource.com/311170Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Tested-by: Olli Etuaho <oetuaho@nvidia.com>