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/method-definition/expected.js

@@ -1 +1,4 @@
-({ x() {} });
+({
+  x() {}
+
+});