ES6: instanceof error messages need updating.

test/mjsunit/messages.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.
 
 // Flags: --stack-size=100 --harmony --harmony-reflect --harmony-regexps
-// Flags: --harmony-simd
+// Flags: --harmony-simd --harmony-instanceof
 
 function test(f, expected, type) {
   try {
     f();
   } catch (e) {
     assertInstanceof(e, type);
     assertEquals(expected, e.message);
     return;
   }
   assertUnreachable("Exception expected");
@@ skipping 126 matching lines @@
 
 // kIncompatibleMethodReceiver
 test(function() {
   Set.prototype.add.call([]);
 }, "Method Set.prototype.add called on incompatible receiver [object Array]",
 TypeError);
 
 // kInstanceofFunctionExpected
 test(function() {
   1 instanceof 1;
-}, "Expecting an object in instanceof check", TypeError);
+}, "right-hand side is not an object", TypeError);
 
 // kInstanceofNonobjectProto
 test(function() {
   function f() {}
   var o = new f();
   f.prototype = 1;
   o instanceof f;
 }, "Function has non-object prototype '1' in instanceof check", TypeError);
 
 // kInvalidInOperatorUse
@@ skipping 281 matching lines @@
   Number(1).toString(100);
 }, "toString() radix argument must be between 2 and 36", RangeError);
 
 
 // === URIError ===
 
 // kURIMalformed
 test(function() {
   decodeURI("%%");
 }, "URI malformed", URIError);