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

perf/server/Gruntfile.js

 module.exports = function(grunt) {
   // Project configuration.
   grunt.initConfig({
     pkg: grunt.file.readJSON('package.json'),
     // Install all the packages listed in the bower.json file.
     shell: {
       bower_install: {
          command: './node_modules/.bin/bower install'
       }
     },
     bower: {
       dev: {
          dest: './third_party/out'
       }
     },
     // Concatenate all the third_party files we use into a single file.
     concat: {
       dist: {
         src: [
           'third_party/out/jquery.js',
           'third_party/bower_components/flot/jquery.flot.js',
           'third_party/bower_components/flot/jquery.flot.crosshair.js',
           'third_party/bower_components/flot/jquery.flot.navigate.js',
+          'third_party/bower_components/observe-js/src/observe.js',
 
           'third_party/out/WeakMap.js',
           'third_party/out/classlist.js',
           'third_party/out/pointerevents.dev.js',
           'third_party/out/MutationObserver.js',
           'third_party/out/CustomElements.js',
           'third_party/out/HTMLImports.js',
 
         ],
         dest: 'res/js/<%= pkg.name %>-debug.js'
@@ skipping 52 matching lines @@
 
   // A target to build an unminified version, for debugging.
   grunt.registerTask('debug-js', ['shell:bower_install', 'bower', 'concat', 'copy:simple']);
 
   // A target to build just the CSS.
   grunt.registerTask('css', ['autoprefixer']);
 
   // A target to build just the CSS.
   grunt.registerTask('test', ['karma']);
 };