Remove angle_standalone from GYP files BUG=angleproject:1462 Change-Id: Ifdd714e2bc1f0a184f63f8ef162facce5286e935 Reviewed-on: https://chromium-review.googlesource.com/365233 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Corentin Wallez <cwallez@chromium.org>