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-generator/src/generators/flow.js

@@ -329,7 +329,11 @@ export function ObjectTypeAnnotation(node: Object) {
     this.token("{");
   }
 
-  const props = node.properties.concat(node.callProperties, node.indexers);
+  // TODO: remove the array fallbacks and instead enforce the types to require an array
+  const props = node.properties.concat(
+    node.callProperties || [],
+    node.indexers || [],
+  );
 
   if (props.length) {
     this.space();