Fix algorithm generics.

lib/src/priority_queue.dart

 // Copyright (c) 2014, 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.
 
 import "dart:collection";
 
+import "utils.dart";
+
 /// A priority queue is a priority based work-list of elements.
 ///
 /// The queue allows adding elements, and removing them again in priority order.
 abstract class PriorityQueue<E> {
   /// Creates an empty [PriorityQueue].
   ///
   /// The created [PriorityQueue] is a plain [HeapPriorityQueue].
   ///
   /// The [comparison] is a [Comparator] used to compare the priority of
   /// elements. An element that compares as less than another element has
@@ skipping 119 matching lines @@
   /// Create a new priority queue.
   ///
   /// The [comparison] is a [Comparator] used to compare the priority of
   /// elements. An element that compares as less than another element has
   /// a higher priority.
   ///
   /// If [comparison] is omitted, it defaults to [Comparable.compare]. If this
   /// is the case, `E` must implement [Comparable], and this is checked at
   /// runtime for every comparison.
   HeapPriorityQueue([int comparison(E e1, E e2)])
-      : comparison = comparison ??
-            ((e1, e2) => (e1 as Comparable).compareTo(e2));
+      : comparison = comparison ?? defaultCompare/*<E>*/();
 
   void add(E element) {
     _add(element);
   }
 
   void addAll(Iterable<E> elements) {
     for (E element in elements) {
       _add(element);
     }
   }
@@ skipping 192 matching lines @@
   ///
   /// Called when the list is full.
   void _grow() {
     int newCapacity = _queue.length * 2 + 1;
     if (newCapacity < _INITIAL_CAPACITY) newCapacity = _INITIAL_CAPACITY;
     List<E> newQueue = new List<E>(newCapacity);
     newQueue.setRange(0, _length, _queue);
     _queue = newQueue;
   }
 }