Shorten autogenerated error message.

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 178 matching lines @@
   var arg_num = 0;
   for (var i = 0; i < format.length; i++) {
     var str = format[i];
     if (str.length == 2 && %_StringCharCodeAt(str, 0) == 0x25) {
       // Two-char string starts with "%".
       var arg_num = (%_StringCharCodeAt(str, 1) - 0x30) >>> 0;
       if (arg_num < 4) {
         // str is one of %0, %1, %2 or %3.
         try {
           str = NoSideEffectToString(args[arg_num]);
+          if (str.length > 256) {
+            str = %SubString(str, 0, 239) + "...<omitted>..." +
+                  %SubString(str, str.length - 2, str.length);
+          }
         } catch (e) {
           if (%IsJSModule(args[arg_num]))
             str = "module";
           else if (IS_SPEC_OBJECT(args[arg_num]))
             str = "object";
           else
             str = "#<error>";
         }
       }
     }
@@ skipping 1138 matching lines @@
     %GetAndClearOverflowedStackTrace(this);
   };
 
   %DefineOrRedefineAccessorProperty(
       boilerplate, 'stack', getter, setter, DONT_ENUM);
 
   return boilerplate;
 }
 
 var kStackOverflowBoilerplate = SetUpStackOverflowBoilerplate();