Fix Reflect.construct wrt proxy, generator, and non-subclass new.target

test/mjsunit/harmony/reflect-construct.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-reflect
 
 
 (function testReflectConstructArity() {
   assertEquals(2, Reflect.construct.length);
 })();
@@ skipping 257 matching lines @@
                                            ["T", "E", "S", "T", "!", "!"]).a);
   assertEquals(10, Reflect.construct(sumStrict,
                                      { 0: 1, 1: 2, 2: 3, 3: 4, length: 4 }).a);
   assertEquals("TEST", Reflect.construct(sumSloppy,
                                          ["T", "E", "S", "T"]).a);
   assertEquals("TEST!!", Reflect.construct(sumSloppy,
                                            ["T", "E", "S", "T", "!", "!"]).a);
   assertEquals(10, Reflect.construct(sumSloppy,
                                      { 0: 1, 1: 2, 2: 3, 3: 4, length: 4 }).a);
 })();
+
+(function() {
+  function* f() { yield 1; yield 2; }
+  function* g() { yield 3; yield 4; }
+  var o = Reflect.construct(f, [], g);
+  assertEquals([1, 2], [...o]);
+  assertTrue(o.__proto__ === g.prototype);
+  assertTrue(o.__proto__ !== f.prototype);
+})();