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/constructor/expected.js

@@ -1,6 +1,5 @@
 var Test = function Test() {
   babelHelpers.classCallCheck(this, Test);
-
   this.state = "test";
 };
 
@@ -21,9 +20,8 @@ var Foo = function (_Bar) {
 
 var ConstructorScoping = function ConstructorScoping() {
   babelHelpers.classCallCheck(this, ConstructorScoping);
-
   var bar = void 0;
   {
     var _bar = void 0;
   }
-};
+};