In Intel Mesa driver, dEQP-GLES31.functional.draw_indirect.random.28 is
faild because of no VAO bound. This patch will fix it by adding VAO
binding.

BUG=angleproject:1595
TEST=dEQP-GLES31.functional.draw_indirect.random.28

Change-Id: I8e4616bc4685839efe299d2a4fad65fa73fde641
Reviewed-on: https://chromium-review.googlesource.com/423438Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>