This simplifies the logic in the Renderer init.

BUG=angle:905

Change-Id: I01bf3701dd85f50e369e2c11e0e2a7cb638ccf00
Reviewed-on: https://chromium-review.googlesource.com/247650Reviewed-by: Brandon Jones <bajones@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>