(early draft) Strict mode - throw exception on assignment to read only property.

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 208 matching lines @@
       strict_octal_literal:         ["Octal literals are not allowed in strict mode."],
       strict_duplicate_property:    ["Duplicate data property in object literal not allowed in strict mode"],
       accessor_data_property:       ["Object literal may not have data and accessor property with the same name"],
       accessor_get_set:             ["Object literal may not have multiple get/set accessors with the same name"],
       strict_lhs_assignment:        ["Assignment to eval or arguments is not allowed in strict mode"],
       strict_lhs_postfix:           ["Postfix increment/decrement may not have eval or arguments operand in strict mode"],
       strict_lhs_prefix:            ["Prefix increment/decrement may not have eval or arguments operand in strict mode"],
       strict_reserved_word:         ["Use of future reserved word in strict mode"],
       strict_delete:                ["Delete of an unqualified identifier in strict mode."],
       strict_delete_property:       ["Cannot delete property '", "%0", "' of ", "%1"],
+      strict_rdonly_property:       ["Cannot assign to read only property '", "%0", "' of ", "%1"],
+      strict_cannot_assign:         ["Cannot assign to read only '", "%0", "' in strict mode"],
     };
   }
   var message_type = %MessageGetType(message);
   var format = kMessages[message_type];
   if (!format) return "<unknown message " + message_type + ">";
   return FormatString(format, message);
 }
 
 
 function GetLineNumber(message) {
@@ skipping 819 matching lines @@
     else throw e;
   }
 }
 
 %FunctionSetName(errorToString, 'toString');
 %SetProperty($Error.prototype, 'toString', errorToString, DONT_ENUM);
 
 // Boilerplate for exceptions for stack overflows. Used from
 // Top::StackOverflow().
 const kStackOverflowBoilerplate = MakeRangeError('stack_overflow', []);