Make argument of List.sort optional with default Comparable.compare.

runtime/lib/array.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.
 
 
 // TODO(srdjan): Use shared array implementation.
 class _ObjectArray<E> implements List<E> {
 
   factory _ObjectArray(int length) native "ObjectArray_allocate";
 
@@ skipping 74 matching lines @@
   }
 
   bool some(bool f(E element)) {
     return Collections.some(this, f);
   }
 
   bool isEmpty() {
     return this.length === 0;
   }
 
-  void sort(int compare(E a, E b)) {
+  void sort([Comparator<E> compare = Comparable.compare]) {
     DualPivotQuicksort.sort(this, compare);
   }
 
   int indexOf(E element, [int start = 0]) {
     return Arrays.indexOf(this, element, start, this.length);
   }
 
   int lastIndexOf(E element, [int start = null]) {
     if (start === null) start = length - 1;
     return Arrays.lastIndexOf(this, element, start);
@@ skipping 121 matching lines @@
   }
 
   bool some(bool f(E element)) {
     return Collections.some(this, f);
   }
 
   bool isEmpty() {
     return this.length === 0;
   }
 
-  void sort(int compare(E a, E b)) {
+  void sort([Comparator<E> compare]) {
     throw const UnsupportedOperationException(
         "Cannot modify an immutable array");
   }
 
   String toString() {
     return Collections.collectionToString(this);
   }
 
   int indexOf(E element, [int start = 0]) {
     return Arrays.indexOf(this, element, start, this.length);
@@ skipping 58 matching lines @@
     if (!hasNext()) {
       throw const NoMoreElementsException();
     }
     return _array[_pos++];
   }
 
   final List<E> _array;
   final int _length;  // Cache array length for faster access.
   int _pos;
 }