Revert "Track if a non-preprocessor token has been seen and validate #extension with it." Causing failures in the GLES2 CTS "build", related to extensions. BUG=483252 BUG=angleproject:989 This reverts commit bbdb9e2259c38454be097ce01505db83db3ad7a8. Change-Id: I3e1ad989af645194c8ee9b9847b2131e289d09e1 Reviewed-on: https://chromium-review.googlesource.com/269403 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>