Based on feedback from Gregg Tavares, relaxed exactly when errors are reported during uniform and varying variable packing.
Merge pull request #137 from kenrussell/packing

Based on feedback from Gregg Tavares, relaxed exactly when errors are re...
Cleanup: Add "use strict"; in most places.
Merge pull request #138 from greggman/use-strict

Cleanup: Add "use strict"; in most places.
Remove unused functions from webgl-test.js
Merge pull request #139 from greggman/remove-unused-funcs

Remove unused functions from webgl-test.js