[tests] make the function expression an iife to run the test

test/mjsunit/es6/promises.js

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 964 matching lines @@
              "subclass/resolve/descendant with transplanted own constructor");
 }());
 
 (function() {
   var thenCalled = false;
 
   var resolve;
   var promise = new Promise(function(res) { resolve = res; });
   resolve({ then() { thenCalled = true; throw new Error(); } });
   assertLater(function() { return thenCalled; }, "resolve-with-thenable");
-});
+})();
 
 (function() {
   var calledWith;
 
   var resolve;
   var p1 = (new Promise(function(res) { resolve = res; }));
   var p2 = p1.then(function(v) {
     return {
       then(resolve, reject) { resolve({ then() { calledWith = v }}); }
     };
   });
 
   resolve({ then(resolve) { resolve(2); } });
   assertLater(function() { return calledWith === 2; },
               "resolve-with-thenable2");
 })();
 
 (function() {
   var p = Promise.resolve();
   var callCount = 0;
   defineProperty(p, "constructor", {
     get: function() { ++callCount; return Promise; }
   });
   p.then();
   assertEquals(1, callCount);
 })();
 
 assertAsyncDone()