Preliminary Harmony weak maps API implementation.

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 183 matching lines @@
       define_disallowed:            ["Cannot define property:", "%0", ", object is not extensible."],
       non_extensible_proto:         ["%0", " is not extensible"],
       handler_non_object:           ["Proxy.", "%0", " called with non-object as handler"],
       handler_trap_missing:         ["Proxy handler ", "%0", " has no '", "%1", "' trap"],
       handler_trap_must_be_callable: ["Proxy handler ", "%0", " has non-callable '", "%1", "' trap"],
       handler_returned_false:       ["Proxy handler ", "%0", " returned false for '", "%1", "' trap"],
       handler_returned_undefined:   ["Proxy handler ", "%0", " returned undefined for '", "%1", "' trap"],
       proxy_prop_not_configurable:  ["Trap ", "%1", " of proxy handler ", "%0", " returned non-configurable descriptor for property ", "%2"],
       proxy_non_object_prop_names:  ["Trap ", "%1", " returned non-object ", "%0"],
       proxy_repeated_prop_name:     ["Trap ", "%1", " returned repeated property name ", "%2"],
+      invalid_weakmap_key:          ["Invalid value used as weak map key"],
       // 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 905 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', []);