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-es2015-function-name/test/fixtures/function-name/modules-4/expected.js

@@ -1,8 +1,9 @@
 export { _foo as foo };
+
 function _foo(bar) {}
 
 var bar = {
   foo: function foo() {
     _foo;
   }
-};
+};