Fix caching paging during read.

pkg/analysis_server/lib/src/index/b_plus_tree.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.
 
 library index.b_plus_tree;
 
 import 'dart:collection';
 
 
 /**
@@ skipping 652 matching lines @@
       } else if (compare > 0) {
         lo = mid + 1;
       } else {
         return mid;
       }
     }
     return lo;
   }
 
   void _insertNotFull(K key, V value, int index) {
-    if (index < keys.length && keys[index] == key) {
+    if (index < keys.length && comparator(keys[index], key) == 0) {
       values[index] = value;
     } else {
       keys.insert(index, key);
       values.insert(index, value);
     }
     tree._writeLeafNode(this);
   }
 }
 
 
@@ skipping 81 matching lines @@
 
 /**
  * A container with information about split during insert.
  */
 class _Split<K, N> {
   final K key;
   final N left;
   final N right;
   _Split(this.key, this.left, this.right);
 }