Moves some checks into helper functions. Refactor only. Bug: angleproject:4959 Change-Id: I08053a96f99baff75eb3954ecbb77e83483eba0f Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2343406Reviewed-by: Charlie Lao <cclao@google.com> Reviewed-by: Tim Van Patten <timvp@google.com> Commit-Queue: Jamie Madill <jmadill@chromium.org>
