Enable the PolicyTest.Disable3DAPIs test on every platform.

This test was enabled only on Mac because the Windows and Linux try bots failed
to create a WebGL context. Recent work on Aura seems to have fixed this, so
the test is getting enabled on every platform now.

BUG=103379

Review URL: https://codereview.chromium.org/72603002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235157 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235157