Remove trailing commas for IE8 support

Author: amccloud

lib/components/ModalPortal.js

@@ -9,12 +9,12 @@ var CLASS_NAMES = {
   overlay: {
     base: 'ReactModal__Overlay',
     afterOpen: 'ReactModal__Overlay--after-open',
-    beforeClose: 'ReactModal__Overlay--before-close',
+    beforeClose: 'ReactModal__Overlay--before-close'
   },
   content: {
     base: 'ReactModal__Content',
     afterOpen: 'ReactModal__Content--after-open',
-    beforeClose: 'ReactModal__Content--before-close',
+    beforeClose: 'ReactModal__Content--before-close'
   }
 };