Wrote functions to convert collections and maps to strings and invoked

corelib/src/implementation/splay_tree.dart

Index: corelib/src/implementation/splay_tree.dart
===================================================================
--- corelib/src/implementation/splay_tree.dart	(revision 4412)
+++ corelib/src/implementation/splay_tree.dart	(working copy)
@@ -1,4 +1,4 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
@@ -234,4 +234,8 @@
     forEach((K k, V v) { list.add(v); });
     return list;
   }
+
+  String toString() {
+    return Maps.mapToString(this);
+  }
 }