end < start must generate an INVALID_VALUE error. Before this patch
INVALID_OPERATION was generated from the check which validated the
actual index range against end and start in this case.

BUG=angleproject:1101
TEST=dEQP-GLES3.functional.negative_api.vertex_array.*
     (few more subtests pass)

Change-Id: Ida9c5a8bc9dc416f1955e9012e5715c0848a0307
Reviewed-on: https://chromium-review.googlesource.com/332143Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>