anchor.diff:      }
     }
   
  -  set(dynamic key, dynamic value) {
  +  void set(dynamic key, dynamic value) {
       String normalized_key = _key(key);
       String normalized_value = JSON.encode(value);
       if (chrome.storage != null) {
  -      _localStorage.set({normalized_key: normalized_value});
  +      chrome.storage.local.set({normalized_key: normalized_value});
       // for dartium
       } else {
         window.localStorage.set(normalized_key, normalized_value);
  
positive.code: import "dart:mirrors";
  
  class localStorage {
    Storage _localStorage;
  
    localStorage() {
      if (chrome.storage != null) {
        _localStorage = chrome.storage.local;
      // for dartium
      } else {
        _localStorage = window.localStorage;
      }
    }
  
    String _key(dynamic key) {
      if (key is! String) {
  
negative.code:     String normalized_key = _key(key);
      if (chrome.storage != null ) {
        Completer completer = new Completer();
        chrome.storage.local.get([normalized_key]).then((Map<String,String> values) {
          var result;
          var value = values[normalized_key];
          if (value == null) {
  