INVALID_VALUE error should be generated not INVALID_OPERATION if indirect
is not a multiple of the size, in basic machine units, of uint.

Meanwhile, we put the validation of indirect before indirect buffer so that
the corresponding deqp cases can pass.

BUG=angleproject:2324

Change-Id: I223ec1893a6dd613f84e51a98f02d5f79482952f
Reviewed-on: https://chromium-review.googlesource.com/929900Reviewed-by: Jiawei Shao <jiawei.shao@intel.com>
Reviewed-by: Yunchao He <yunchao.he@intel.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>