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-classes/test/fixtures/spec/super-function-fallback/expected.js

@@ -1,5 +1,4 @@
 var Test = function Test() {
   babelHelpers.classCallCheck(this, Test);
-
   babelHelpers.get(Test.prototype.__proto__ || Object.getPrototypeOf(Test.prototype), "hasOwnProperty", this).call(this, "test");
-};
+};