Validate invariance of built-in variables when linking According to ESSL 1.00.17 paragraph 4.6.4 BUG=angleproject:1876 Change-Id: I61e142c31dce11eec28fe240a9bc9ce2c632daf6 Reviewed-on: https://chromium-review.googlesource.com/446870 Reviewed-by: Kenneth Russell <kbr@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Yuly Novikov <ynovikov@chromium.org>