[#89576510] Fix configuration of es6-promise polyfill.

We were using require, but it wasn't doing what it would be expected to do.
Now we are using the no-require polyfill initialization.
stefanpenner/es6-promise#75

apps/dg/libraries/es6-promise-polyfill.js

@@ -1,2 +1,3 @@
 // Polyfill the Promise object.
-window.Promise = window.Promise || require('libraries/es6-promise-2.0.1.js');
+sc_require('es6-promise-2.0.1.js');
+window.Promise = window.Promise || ES6Promise.Promise;