simplify return logic; remove typeof check (#106)

http://stackoverflow.com/a/4725697/2419669

src/handleActions.js

@@ -6,7 +6,5 @@ export default function handleActions(handlers, defaultState) {
   const reducers = ownKeys(handlers).map(type => handleAction(type, handlers[type]));
   const reducer = reduceReducers(...reducers);
 
-  return typeof defaultState !== 'undefined'
-    ? (state = defaultState, action) => reducer(state, action)
-    : reducer;
+  return (state = defaultState, action) => reducer(state, action);
 }