Revert "Tweaked regenerator hackery to work in CodeCombat chaos environment with the web worker."

This reverts commit efe88c28ae80f0cd2f3339ea2fc27bb73c2a094b.
Revert "Replaced traceur with regenerator."

This reverts commit 3466961717b39bab2c8f3e356e6ecfa340006225.
Reverted to traceur, as regenerator was super slow. Added trimRight() fallback.