Add checks to runtime functions.

src/messages.js

 // Copyright 2012 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 184 matching lines @@
       "proto_non_object",             ["Proxy.", "%0", " called with non-object as prototype"],
       "trap_function_expected",       ["Proxy.", "%0", " called with non-function for '", "%1", "' trap"],
       "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 from '", "%1", "' trap"],
       "handler_returned_undefined",   ["Proxy handler ", "%0", " returned undefined from '", "%1", "' trap"],
       "proxy_prop_not_configurable",  ["Proxy handler ", "%0", " returned non-configurable descriptor for property '", "%2", "' from '", "%1", "' trap"],
       "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"],
+      "not_date_object",              ["this is not a Date object."],

[Erik Corry, 2012/09/07 09:22:33]

We normally use the word "Receiver", rather than 'this'.  That would also let
you capitalize it correctly.

       // RangeError
       "invalid_array_length",         ["Invalid array length"],
       "stack_overflow",               ["Maximum call stack size exceeded"],
       "invalid_time_value",           ["Invalid time value"],
       // SyntaxError
       "unable_to_parse",              ["Parse error"],
       "invalid_regexp_flags",         ["Invalid flags supplied to RegExp constructor '", "%0", "'"],
       "invalid_regexp",               ["Invalid RegExp pattern /", "%0", "/"],
       "illegal_break",                ["Illegal break statement"],
       "illegal_continue",             ["Illegal continue statement"],
@@ skipping 1044 matching lines @@
     throw e;
   }
 }
 
 
 InstallFunctions($Error.prototype, DONT_ENUM, ['toString', ErrorToString]);
 
 // Boilerplate for exceptions for stack overflows. Used from
 // Isolate::StackOverflow().
 var kStackOverflowBoilerplate = MakeRangeError('stack_overflow', []);