Also remove mCurPointGeometryShader and instead pass the program to
drawArrays.

BUG=angle:872

Change-Id: If55517e81d9234705eabcc0e5be7b5b492858e08
Reviewed-on: https://chromium-review.googlesource.com/241421Tested-by: Gregoire Payen de La Garanderie <Gregory.Payen@imgtec.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>