After this patch, ANGLE no longer accepts constructors where any of
multiple parameters is sampler or void.

Also, structure array constructors with just one parameter are now
accepted.

Error message for a constructor with no parameters is also more
informative than before.

BUG=angleproject:1193
TEST=angle_unittests

Change-Id: I6b897973448cf500096f612b3b95dcc23aebc716
Reviewed-on: https://chromium-review.googlesource.com/311590Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tryjob-Request: Olli Etuaho <oetuaho@nvidia.com>
Tested-by: Olli Etuaho <oetuaho@nvidia.com>