Bug 1309 non-extensible objects have immutable __Proto__

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 172 matching lines @@
       instanceof_nonobject_proto:   ["Function has non-object prototype '", "%0", "' in instanceof check"],
       null_to_object:               ["Cannot convert null to object"],
       reduce_no_initial:            ["Reduce of empty array with no initial value"],
       getter_must_be_callable:      ["Getter must be a function: ", "%0"],
       setter_must_be_callable:      ["Setter must be a function: ", "%0"],
       value_and_accessor:           ["Invalid property.  A property cannot both have accessors and be writable or have a value: ", "%0"],
       proto_object_or_null:         ["Object prototype may only be an Object or null"],
       property_desc_object:         ["Property description must be an object: ", "%0"],
       redefine_disallowed:          ["Cannot redefine property: ", "%0"],
       define_disallowed:            ["Cannot define property, object is not extensible: ", "%0"],
+      non_extensible_proto:         ["%0", " is not extensible"],
       // RangeError
       invalid_array_length:         ["Invalid array length"],
       stack_overflow:               ["Maximum call stack size exceeded"],
       // SyntaxError
       unable_to_parse:              ["Parse error"],
       duplicate_regexp_flag:        ["Duplicate RegExp flag ", "%0"],
       invalid_regexp:               ["Invalid RegExp pattern /", "%0", "/"],
       illegal_break:                ["Illegal break statement"],
       illegal_continue:             ["Illegal continue statement"],
       illegal_return:               ["Illegal return statement"],
@@ skipping 878 matching lines @@
     else throw e;
   }
 }
 
 
 InstallFunctions($Error.prototype, DONT_ENUM, ['toString', errorToString]);
 
 // Boilerplate for exceptions for stack overflows. Used from
 // Isolate::StackOverflow().
 const kStackOverflowBoilerplate = MakeRangeError('stack_overflow', []);