Some texture.mipmap.2d.projected are passing and 
fbo.api.valid_texcube_attachments seems to pass.

BUG=angleproject:1026
BUG=angleproject:1020

Change-Id: I46ada896978cbb0a3bcbfb3985a5a50e4095ab98
Reviewed-on: https://chromium-review.googlesource.com/308391
Tryjob-Request: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>