6.0.0

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.

packages/babel-generator/test/fixtures/comments/function-block-line-comment/expected.js

@@ -1,6 +1,6 @@
-!function () {}, //
-42;
-!{ get 42() {}, //
-  foo: 42 };
-(function () {});
-//
+!function () {} //
+, 42;
+!{ get 42() {} //
+  , foo: 42 };
+(function () {} //
+);