new classes: assert that constructors are not callable and rewrite 'return;'

test/mjsunit/harmony/classes-experimental.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: --experimental-classes --harmony-classes
 
 'use strict';
 
 class Base {
   constructor(a, b) {
@@ skipping 16 matching lines @@
     assertSame(a + b, this.prp);
     assertSame(undefined, this.prp1);
     assertFalse(this.hasOwnProperty("prp1"));
     return this;
   }
 }
 
 let b = new Base(1, 2);
 assertSame(3, b.prp);
 
+
 let s = new Subclass(2, -1);
 assertSame(1, s.prp);
 assertSame(undefined, s.prp1);
 assertFalse(s.hasOwnProperty("prp1"));
 
 class Subclass2 extends Base {
-  constructor() {
+  constructor(x) {
     super(1,2);
 
+    if (x < 0) return;
+
     let called = false;
     function tmp() { called = true; return 3; }
     var exn = null;
     try {
       super(tmp(),4);
     } catch(e) { exn = e; }
     assertTrue(exn !== null);
     assertFalse(called);
   }
 }
 
-new Subclass2();
+var s2 = new Subclass2(1);
+assertSame(3, s2.prp);
+
+var s3 = new Subclass2(-1);
+assertSame(3, s3.prp);
+
+assertThrows(function() { Subclass.call(new Object(), 1, 2); }, TypeError);
+assertThrows(function() { Base.call(new Object(), 1, 2); }, TypeError);