Each new entry point corresponds to one of the variable types:
varyings, attributes, uniforms, output variables, and interface
blocks. They return a pointer to the vector with all of the
parsed variables, which then the app can copy to its own memory.

Currently we do not support the staticUse field in the HLSL
translator.

BUG=angle:466

Change-Id: I7dc09e761ab070feef5360ad27740110c44853b3
Reviewed-on: https://chromium-review.googlesource.com/208750Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Reviewed-by: Nicolas Capens <capn@chromium.org>