Remove whitespace generation (#5833)

* 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

packages/babel-plugin-transform-react-jsx/test/fixtures/react/display-name-variable-declaration/expected.js

@@ -1,7 +1,6 @@
 var Component = React.createClass({
   displayName: "Component",
-
   render: function render() {
     return null;
   }
-});
+});