pkg/serialization: cleanup

pkg/serialization/lib/src/serialization_helpers.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * This contains extra functions and classes useful for implementing
  * serialiation. Some or all of these will be removed once the functionality is
  * available in the core library.
  */
 library serialization_helpers;
@@ skipping 187 matching lines @@
   void operator []=(K key, V value) {
     var index = _indexOf(key);
     if (index == -1) {
       keys.add(key);
       values.add(value);
     } else {
       values[index] = value;
     }
   }
 
-  putIfAbsent(K key, Function ifAbsent) {
+  V putIfAbsent(K key, Function ifAbsent) {
     var index = _indexOf(key);
     if (index == -1) {
       keys.add(key);
       values.add(ifAbsent());
       return values.last;
     } else {
       return values[index];
     }
   }
 
-  _indexOf(K key) {
+  int _indexOf(K key) {
     // Go backwards on the guess that we are most likely to access the most
     // recently added.
     // Make strings and primitives unique
     var compareEquality = isPrimitive(key);
     for (var i = keys.length - 1; i >= 0; i--) {
       var equal = compareEquality ? key == keys[i] : identical(key, keys[i]);
       if (equal) return i;
     }
     return -1;
   }
@@ skipping 15 matching lines @@
   int get length => keys.length;
   void clear() {
     keys.clear();
     values.clear();
   }
   bool get isEmpty => keys.isEmpty;
   bool get isNotEmpty => !isEmpty;
 
   // Note that this is doing an equality comparison.
   bool containsValue(x) => values.contains(x);
+
+  void addAll(Map<K, V> other) {
+    other.forEach((K key, V value) {
+      this[key] = value;
+    });
+  }
 }