ES6: Error functions should extend Error

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 kMessages = {
   // Error
   cyclic_proto:                  ["Cyclic __proto__ value"],
   code_gen_from_strings:         ["%0"],
@@ skipping 1154 matching lines @@
       // 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.
       var ErrorPrototype = function() {};
       %FunctionSetPrototype(ErrorPrototype, $Object.prototype);
       %FunctionSetInstanceClassName(ErrorPrototype, 'Error');
       %FunctionSetPrototype(f, new ErrorPrototype());
     } else {
       %FunctionSetPrototype(f, new $Error());
+      %InternalSetPrototype(f, $Error);
     }
     %FunctionSetInstanceClassName(f, 'Error');
     %AddNamedProperty(f.prototype, 'constructor', f, DONT_ENUM);
-    %AddNamedProperty(f.prototype, "name", name, DONT_ENUM);
+    %AddNamedProperty(f.prototype, 'name', name, DONT_ENUM);
     %SetCode(f, function(m) {
       if (%_IsConstructCall()) {
         try { captureStackTrace(this, f); } catch (e) { }
         // Define all the expected properties directly on the error
         // object. This avoids going through getters and setters defined
         // on prototype objects.
         if (!IS_UNDEFINED(m)) {
           %AddNamedProperty(this, 'message', ToString(m), DONT_ENUM);
         }
       } else {
@@ skipping 88 matching lines @@
 function SetUpStackOverflowBoilerplate() {
   var boilerplate = MakeRangeError('stack_overflow', []);
 
   %DefineAccessorPropertyUnchecked(
       boilerplate, 'stack', StackTraceGetter, StackTraceSetter, DONT_ENUM);
 
   return boilerplate;
 }
 
 var kStackOverflowBoilerplate = SetUpStackOverflowBoilerplate();