Remove sh::InterfaceBlock::registerIndex. This value is HLSL-only and we can use the new query API to hide it from GLSL programs. BUG=angle:466 Change-Id: I75dc2fbbf1b29b1f6d561568174a15dea1f5b130 Reviewed-on: https://chromium-review.googlesource.com/207250 Tested-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Zhenyao Mo <zmo@chromium.org>