Update WebGL conformance expectations for tests that are now passing.
tex-image-and-sub-image-2d-with-video-{rgb565,rgba4444,rgba5551} are
passing in content_shell on all devices except the Nexus 6.
texture-npot-video is passing on the Nexus 6 now.
gl-uniform-arrays, empty_main.vert and gl_position_unset.vert are
passing on the new Nexus 5, 6 and 9 bots.
BUG=315976,369300,499555
R=zmo@chromium.org
NOTRY=true
Review URL: https://codereview.chromium.org/
1196683004
Cr-Commit-Position: refs/heads/master@{#335303}