[builtins] Get rid of a few %_ClassOf uses.

src/js/harmony-simd.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.
 
 (function(global, utils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 44 matching lines @@
 endmacro
 
 SIMD_ALL_TYPES(DECLARE_GLOBALS)
 
 macro DECLARE_COMMON_FUNCTIONS(NAME, TYPE, LANES)
 function NAMECheckJS(a) {
   return %NAMECheck(a);
 }
 
 function NAMEToString() {
-  if (typeof(this) !== 'TYPE' && %_ClassOf(this) !== 'NAME') {
+  var value = %_ValueOf(this);
+  if (typeof(value) !== 'TYPE') {
     throw MakeTypeError(kIncompatibleMethodReceiver,
                         "NAME.prototype.toString", this);
   }
-  var value = %_ValueOf(this);
   var str = "SIMD.NAME(";
   str += %NAMEExtractLane(value, 0);
   for (var i = 1; i < LANES; i++) {
     str += ", " + %NAMEExtractLane(value, i);
   }
   return str + ")";
 }
 
 function NAMEToLocaleString() {
-  if (typeof(this) !== 'TYPE' && %_ClassOf(this) !== 'NAME') {
+  var value = %_ValueOf(this);
+  if (typeof(value) !== 'TYPE') {
     throw MakeTypeError(kIncompatibleMethodReceiver,
                         "NAME.prototype.toLocaleString", this);
   }
-  var value = %_ValueOf(this);
   var str = "SIMD.NAME(";
   str += %NAMEExtractLane(value, 0).toLocaleString();
   for (var i = 1; i < LANES; i++) {
     str += ", " + %NAMEExtractLane(value, i).toLocaleString();
   }
   return str + ")";
 }
 
 function NAMEValueOf() {
-  if (typeof(this) !== 'TYPE' && %_ClassOf(this) !== 'NAME') {
+  var value = %_ValueOf(this);
+  if (typeof(value) !== 'TYPE') {
     throw MakeTypeError(kIncompatibleMethodReceiver,
                         "NAME.prototype.valueOf", this);
   }
-  return %_ValueOf(this);
+  return value;
 }
 
 function NAMEExtractLaneJS(instance, lane) {
   return %NAMEExtractLane(instance, lane);
 }
 endmacro
 
 SIMD_ALL_TYPES(DECLARE_COMMON_FUNCTIONS)
 
 macro DECLARE_SHIFT_FUNCTIONS(NAME, TYPE, LANES)
@@ skipping 803 matching lines @@
   to.Bool32x4ToString = Bool32x4ToString;
   to.Int16x8ToString = Int16x8ToString;
   to.Uint16x8ToString = Uint16x8ToString;
   to.Bool16x8ToString = Bool16x8ToString;
   to.Int8x16ToString = Int8x16ToString;
   to.Uint8x16ToString = Uint8x16ToString;
   to.Bool8x16ToString = Bool8x16ToString;
 });
 
 })