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-async-to-module-method/test/fixtures/bluebird-coroutines/arrow-function/expected.js

@@ -1,4 +1,5 @@
 import { coroutine as _coroutine } from "bluebird";
+
 _coroutine(function* () {
   yield foo();
-})();
+})();

packages/babel-plugin-transform-async-to-module-method/test/fixtures/bluebird-coroutines/class/expected.js

@@ -1,8 +1,10 @@
 import { coroutine as _coroutine } from "bluebird";
+
 class Foo {
   foo() {
     return _coroutine(function* () {
       var wat = yield bar();
     })();
   }
-}
+
+}

packages/babel-plugin-transform-async-to-module-method/test/fixtures/bluebird-coroutines/expression/expected.js

@@ -1,4 +1,5 @@
 import { coroutine as _coroutine } from "bluebird";
+
 var foo = (() => {
   var _ref = _coroutine(function* () {
     var wat = yield bar();
@@ -7,4 +8,4 @@ var foo = (() => {
   return function foo() {
     return _ref.apply(this, arguments);
   };
-})();
+})();

packages/babel-plugin-transform-async-to-module-method/test/fixtures/bluebird-coroutines/named-expression/expected.js

@@ -1,4 +1,5 @@
 import { coroutine as _coroutine } from "bluebird";
+
 var foo = (() => {
   var _ref = _coroutine(function* () {
     console.log(bar);
@@ -9,4 +10,4 @@ var foo = (() => {
   }
 
   return bar;
-})();
+})();