dart 'commit' is deprecated and shouldn't be used

As per the example I am trying to commit the SharedPreference. But getting warning as below screenshot attached.

<img width="779" alt="screen shot 2018-11-13 at 3 50 53 pm" src="https://user-images.githubusercontent.com/5895976/48407161-34953000-e75c-11e8-81f9-08a3f92cc02c.png">
