[runtime] Remove useless %_IsUndetectableObject intrinsic.

src/messages.js

 // Copyright 2012 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.
 
 // -------------------------------------------------------------------
 
 var $errorToString;
 var $getStackTraceLine;
 var $internalErrorSymbol;
 var $messageGetPositionInLine;
@@ skipping 64 matching lines @@
 var GlobalError;
 var GlobalTypeError;
 var GlobalRangeError;
 var GlobalURIError;
 var GlobalSyntaxError;
 var GlobalReferenceError;
 var GlobalEvalError;
 
 
 function NoSideEffectsObjectToString() {
-  if (IS_UNDEFINED(this) && !IS_UNDETECTABLE(this)) return "[object Undefined]";
+  if (IS_UNDEFINED(this)) return "[object Undefined]";
   if (IS_NULL(this)) return "[object Null]";
   return "[object " + %_ClassOf(TO_OBJECT(this)) + "]";
 }
 
 
 function NoSideEffectToString(obj) {
   if (IS_STRING(obj)) return obj;
   if (IS_NUMBER(obj)) return %_NumberToString(obj);
   if (IS_BOOLEAN(obj)) return obj ? 'true' : 'false';
   if (IS_UNDEFINED(obj)) return 'undefined';
@@ skipping 974 matching lines @@
   // Define accessors first, as this may fail and throw.
   ObjectDefineProperty(obj, 'stack', { get: StackTraceGetter,
                                        set: StackTraceSetter,
                                        configurable: true });
   %CollectStackTrace(obj, cons_opt ? cons_opt : captureStackTrace);
 };
 
 GlobalError.captureStackTrace = captureStackTrace;
 
 });