This is needed in preparation of implementing DispatchCompute, which
will need to set some of the same state as draw calls, but not
everything.

Also move setTextureCubemapSeamlessEnabled to onMakeCurrent, this way
it doesn't need to be called on every draw call. Overall this patch
doesn't have a measurable performance impact.

BUG=angleproject:1442
TEST=angle_perftests, angle_end2end_tests

Change-Id: I9958bfe7bf895b3cd805e3146a8f74d28ff2835e
Reviewed-on: https://chromium-review.googlesource.com/438349Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>