When converting an mjsunit exception to a string, include the stack

test/mjsunit/mjsunit.js

 // Copyright 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 21 matching lines @@
 }
 
 /*
  * This file is included in all mini jsunit test cases.  The test
  * framework expects lines that signal failed tests to start with
  * the f-word and ignore all other lines.
  */
 
 
 MjsUnitAssertionError.prototype.toString = function () {
-  return this.message;
+  return this.message + "\n\nStack: " + this.stack;
 };
 
 
 // Expected and found values the same objects, or the same primitive
 // values.
 // For known primitive values, please use assertEquals.
 var assertSame;
 
 // Expected and found values are identical primitive values or functions
 // or similarly structured objects (checking internal properties
@@ skipping 335 matching lines @@
     if (sync_opt === undefined) sync_opt = "";
     assertTrue(OptimizationStatus(fun, sync_opt) !== 1, name_opt);
   }
 
   assertOptimized = function assertOptimized(fun, sync_opt, name_opt) {
     if (sync_opt === undefined) sync_opt = "";
     assertTrue(OptimizationStatus(fun, sync_opt) !== 2, name_opt);
   }
 
 })();