This cleans up the syntax somewhat. Also place some more of the
helper methods in the header.

BUG=angleproject:963

Change-Id: I62419095a7b65486f54d74791027594e8e595e48
Reviewed-on: https://chromium-review.googlesource.com/263629Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>