remove whitespace from the end of the last newline and improve newlines for switches

test/fixtures/generation/comments/2-space-multi-comment-with-space/expected.js

@@ -1,4 +1,5 @@
 function test() {
+
   /*
    * this is comment
    */

test/fixtures/transformation/es6-block-scoping/for-break-continue-return/expected.js

@@ -20,8 +20,10 @@
     switch (_ret) {
       case "continue":
         continue;
+
       case "break":
         break;
+
       default:
         if (typeof _ret === "object") return _ret.v;
     }