Fix AsyncStorageExample

Comment out React Native's use of non-standard `done()` method, which
isn't available on `async` functions even though it is polyfilled for
the global Promise.

packages/examples/src/RNTester/AsyncStorageExample.js

@@ -29,7 +29,7 @@ class BasicStorageExample extends React.Component<{}, $FlowFixMeState> {
   };
 
   componentDidMount() {
-    this._loadInitialState().done();
+    this._loadInitialState()//.done();
   }
 
   _loadInitialState = async () => {