* Remove whitespace generation and rely on default printing
Changes to printing:
* Add newline after last empty SwitchCase
* Add newlines around block comments if they are non-flow comments or contain newlines
* Fix a few more fixtures
* Transform do-expressions on exit
This allows other transforms (notably, block scoping) to do their magic
first, possibly saving closures.
Also fixes a bug with declaring duplicate bindings (de-opts now).
* Use strict in exec test
* lint
