Simplify default export

This removes unnecessary variable declarations where the default object is an object.

src/ol/source/State.js

@@ -1,15 +1,14 @@
 /**
  * @module ol/source/State
  */
+
 /**
  * State of the source, one of 'undefined', 'loading', 'ready' or 'error'.
  * @enum {string}
  */
-var _ol_source_State_ = {
+export default {
   UNDEFINED: 'undefined',
   LOADING: 'loading',
   READY: 'ready',
   ERROR: 'error'
 };
-
-export default _ol_source_State_;