If one of the parameters is a vec/mat, expand it into scalars.

This is to work around Linux NVIDIA/AMD and Mac NVIDIA driver bugs.

BUG=angle:695
TEST=webgl conformance test

Change-Id: I35e1e25167d99f873dcb03bfb57a30e84b1aeed5
Reviewed-on: https://chromium-review.googlesource.com/207479Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Zhenyao Mo <zmo@chromium.org>