Classes: Add support for toString

test/mjsunit/harmony/classes.js

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --harmony
 
 (function TestBasics() {
   var C = class C {}
   assertEquals(typeof C, 'function');
   assertEquals(C.__proto__, Function.prototype);
@@ skipping 147 matching lines @@
   class C {
     constructor() {
       assertThrows(function() {
         C = 42;
       }, ReferenceError);
     }
   }
   new C();
 })();
 */
+
+
+(function TestToString() {
+  class C {}
+  assertEquals('class C {}', C.toString());
+
+  class D { constructor() { 42; } }
+  assertEquals('class D { constructor() { 42; } }', D.toString());
+
+  class E { x() { 42; } }
+  assertEquals('class E { x() { 42; } }', E.toString());
+})();