[runtime] Let native setters have a return value.

test/mjsunit/es6/reflect.js

 // Copyright 2015 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.
 
 // TODO(neis): Test with proxies.
 
 
 
 ////////////////////////////////////////////////////////////////////////////////
 // (Auxiliaries)
@@ skipping 255 matching lines @@
     Object.defineProperty(receiver2, "bla",
         {configurable: false, writable: true, value: true});
     Object.defineProperty(receiver2, "not_in_target",
         {configurable: false, writable: true, value: true});
     assertTrue(Reflect.set(target, "bla", value, receiver2));
     assertTrue(Reflect.set(target, "not_in_target", value, receiver2));
   }
 })();
 
 
+(function testReflectSetArrayLength() {
+  var y = [];
+  Object.defineProperty(y, 0, {value: 42, configurable: false});
+  assertFalse(Reflect.set(y, 'length', 0));
+  assertTrue(Reflect.set(y, 'length', 2));
+})();
+
+
 
 ////////////////////////////////////////////////////////////////////////////////
 // Reflect.has
 
 
 (function testReflectHasArity() {
   assertEquals(2, Reflect.has.length);
 })();
 
 
@@ skipping 59 matching lines @@
 (function testReflectDefinePropertyKeyConversion() {
   var target = {};
   var a = { [Symbol.toPrimitive]: function() { return "bla" } };
   var b = { [Symbol.toPrimitive]: function() { throw "gaga" } };
   assertTrue(Reflect.defineProperty(target, a, {value: 42}));
   assertEquals(target.bla, 42);
   assertThrowsEquals(function() { Reflect.defineProperty(target, b); }, "gaga");
 })();
 
 
+(function testReflectDefinePropertyArrayLength() {
+  var y = [];
+  Object.defineProperty(y, 0, {value: 42, configurable: false});
+  assertFalse(Reflect.defineProperty(y, 'length', {value: 0}));
+  assertTrue(Reflect.defineProperty(y, 'length', {value: 2}));
+})();
+
+
 // See reflect-define-property.js for further tests.
 
 
 
 ////////////////////////////////////////////////////////////////////////////////
 // Reflect.deleteProperty
 
 
 (function testReflectDeletePropertyArity() {
   assertEquals(2, Reflect.deleteProperty.length);
@@ skipping 203 matching lines @@
   assertThrows(function() { Reflect.preventExtensions(); }, TypeError);
   assertThrows(function() { Reflect.preventExtensions(42); }, TypeError);
   assertThrows(function() { Reflect.preventExtensions(null); }, TypeError);
 })();
 
 
 // See reflect-prevent-extensions.js for further tests.
 
 // TODO(neis): Need proxies to test the situation where
 // [[preventExtensions]] returns false.