Tweaked semantics of error prototype.

src/messages.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 616 matching lines @@
   var name = f.name;
   %SetProperty(global, name, f, DONT_ENUM);
   this['$' + name] = f;
   // Configure the error function.
   if (name == 'Error') {
     // The prototype of the Error object must itself be an error.
     // However, it can't be an instance of the Error object because
     // it hasn't been properly configured yet.  Instead we create a
     // special not-a-true-error-but-close-enough object.
     function ErrorPrototype() {}
+    %FunctionSetPrototype(ErrorPrototype, $Object.prototype);
     %FunctionSetInstanceClassName(ErrorPrototype, 'Error');
     %FunctionSetPrototype(f, new ErrorPrototype());
   } else {
     %FunctionSetPrototype(f, new $Error());
   }
   %FunctionSetInstanceClassName(f, 'Error');
   %SetProperty(f.prototype, 'constructor', f, DONT_ENUM);
   f.prototype.name = name;
   %SetCode(f, function(m) {
     if (%IsConstructCall()) {
@@ skipping 29 matching lines @@
     return this.name + ": " + FormatMessage({ type: type, args: this.arguments });
   }
   var message = this.message;
   return this.name + (message ? (": " + message) : "");
 }, DONT_ENUM);
 
 
 // Boilerplate for exceptions for stack overflows. Used from
 // Top::StackOverflow().
 const kStackOverflowBoilerplate = MakeRangeError('stack_overflow', []);