Implement more of the JavaScript GL API.

Right now I am just translating as directly as possible from the C spinning cube demo -- once it all works I will circle back through and refine the JavaScript.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/114883003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242230 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242230