Adds support for GLES 3.0 feature which adds gl_VertexID and gl_InstanceID built-in variables to vertex shader. Bug: angleproject:3221 Change-Id: I372d7ac34bed376b506e327725f0eca2513852fa Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1646735 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>
