The Compiler base class now stores all the shader variables and
interface block information, instead of duplicating the information
in the HLSL translator.

BUG=angle:466

Change-Id: Ia69079fde64fbd6b0cbfc66defd5e37d99ee3e6e
Reviewed-on: https://chromium-review.googlesource.com/206020Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Reviewed-by: Nicolas Capens <capn@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>