This cleans up the code slightly and removes a few if checks.
Also fixes a potential edge case with ProgramBinary called on a program
that is in-use.

Bug: angleproject:2763
Change-Id: Ibe0ab20ed44f593bb6c2b0612871680a7df1a15f
Reviewed-on: https://chromium-review.googlesource.com/1254041Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>