Implementing gl_InstanceID in the HLSL compiler. Fixes: dEQP-GLES3.functional.instanced.draw_arrays_instanced.instance_id dEQP-GLES3.functional.instanced.draw_arrays_instanced.mixed dEQP-GLES3.functional.instanced.draw_elements_instanced.instance_id dEQP-GLES3.functional.instanced.draw_elements_instanced.mixed BUG=angle:601 Change-Id: I6e120eebc90d00e025fc58f096064e6ed1da826b Reviewed-on: https://chromium-review.googlesource.com/246911 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Gregoire Payen de La Garanderie <Gregory.Payen@imgtec.com> Reviewed-by: Zhenyao Mo <zmo@chromium.org>