Add the Polymer object observe library and add a test that it works.

perf/server/karma.conf.js

 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be found
 // in the LICENSE file.
 //
 // Use of this source code is governed by a BSD-style
 //  license that can be found in the LICENSE file.
 //
 // Karma configuration
 
 var browsers;
@@ skipping 12 matching lines @@
     // base path, that will be used to resolve files and exclude
     basePath: '',
 
 
     // frameworks to use
     frameworks: ['mocha', 'chai'],
 
 
     // list of files / patterns to load in the browser
     files: [
+      'res/js/perf.js',
       'res/js/logic.js',
       'tests/*.js'
     ],
 
 
     // list of files to exclude
     exclude: [
     ],
 
 
@@ skipping 28 matching lines @@
     captureTimeout: 60000,
 
 
     // Continuous Integration mode
     // if true, it capture browsers, run tests and exit
     //
     // This can be over-ridden by command-line flag when running Karma.
     singleRun: true
   });
 };