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-compat/test/fixtures/react-compat/convert-component/expected.js

@@ -1 +1,3 @@
-var x = Component({ foo: "bar" }, Namespace.Component(null));
+var x = Component({
+  foo: "bar"
+}, Namespace.Component(null));