only load when in Node when needed

guybedford · guybedford · commit a45bb096643f · 2015-04-05T02:01:01.000+02:00
diff --git a/index.js b/index.js
@@ -1,4 +1,5 @@
-require('when');
+if (typeof Promise === 'undefined')
+  require('when');
 
 var System = require('./dist/es6-module-loader.src');
 
