chore(build): replace traceur-runtime with es6-shim.

This removes traceur as a dependency for the t push -f
angular2 build.

Closes #4148

modules/benchpress/index.ts

@@ -1,5 +1,5 @@
 require('reflect-metadata');
-require('traceur/bin/traceur-runtime');
+require('es6-shim');
 module.exports = require('./benchpress.js');
 // when bundling benchpress to one file, this is used
 // for getting exports out of browserify's scope.

modules/benchpress/package.json

@@ -10,7 +10,6 @@
   "repository": <%= JSON.stringify(packageJson.repository) %>,
   "dependencies": {
     "angular2": "<%= packageJson.version %>",
-    "traceur": "<%= packageJson.dependencies.traceur %>",
     "selenium-webdriver": "<%= packageJson.dependencies['selenium-webdriver'] %>",
     "reflect-metadata": "<%= packageJson.dependencies['reflect-metadata'] %>"
   },

modules/benchpress/test/firefox_extension/conf.ts

@@ -1,5 +1,5 @@
 /// <reference path="../../../angular2/typings/node/node.d.ts" />
-require('traceur/bin/traceur-runtime.js');
+require('es6-shim/es6-shim.js');
 require('reflect-metadata');
 var testHelper = require('../../src/firefox_extension/lib/test_helper.js');