Added es6-promise polyfill in browsers.

Author: Aamod Pisat

src/runtime/node/http.js

@@ -1,4 +1,6 @@
-require('es6-promise').polyfill();
+import ES6Promise from 'es6-promise';
 import fetch from 'isomorphic-fetch';
 
+ES6Promise.polyfill();
+
 export default fetch;

src/runtime/react-native/http.js

@@ -1,2 +1,7 @@
+import ES6Promise from 'es6-promise';
+import fetch from 'isomorphic-fetch';
+
+ES6Promise.polyfill();
+
 export default fetch;
 

src/runtime/web/http.js

@@ -1,4 +1,6 @@
-require('es6-promise').polyfill();
+import ES6Promise from 'es6-promise';
 import fetch from 'isomorphic-fetch';
 
+ES6Promise.polyfill();
+
 export default fetch;