The cloning caused comments that where added to the original node to be persisted into
the cloned node.
Espree/Acorn does not have any cloning, that's why it is working there.
This change omits comments when cloning, as removing the cloning
causes tests in babel to fail.
I'm extremely stupid and didn't commit as I go. To anyone reading this
I'm extremely sorry. A lot of these changes are very broad and I plan on
releasing Babel 6.0.0 today live on stage at Ember Camp London so I'm
afraid I couldn't wait. If you're ever in London I'll buy you a beer
(or assorted beverage!) to make up for it, also I'll kiss your feet and
give you a back massage, maybe.
