No review because this is mostly just syncing us with the upstream,
https://cvs.khronos.org/svn/repos/registry/trunk/public/webgl/sdk/tests/
as well as adjusting to test harness changes (now loading test lists asynchronously) and a patch to the harness itself which I'll send upstream (see fix-webgl-harness-async.patch)
Added some code to print to dump output of WebGL mochitest failures. Also added
special code to handle incorrect reference images. It will now provide the user
with a way to compare the reference and actual drawings.