This paves the way for returning ES3-specific info from the shader
translator with the new query methods.

BUG=angle:466

Change-Id: Ib13cdb604854cdf11e9dc00dd94f18eadc946561
Reviewed-on: https://chromium-review.googlesource.com/206770Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>