Remove ShGetVariableInfo() and related code.

BUG=angle:775
TEST=chromium builds and runs fine

Change-Id: Ic62d3a3c9a8f034880b77a96f7f1c6be2691985e
Reviewed-on: https://chromium-review.googlesource.com/226004
Tested-by: Zhenyao Mo <zmo@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>