Verify that the compiler has been initialized before freeing it. BUG=angle:625 Change-Id: I8bba0dea26eacf02df4568cfb6840aa332bd0df8 Reviewed-on: https://chromium-review.googlesource.com/197655 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>