Add getMinimum, getMaximum, getPreceding and getSucceeding to SplayTree.

tests/corelib/src/SplayTreeTest.dart

 // Copyright (c) 2011, 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.
 
 // Dart test for Splaytrees.
 #library("SplayTreeTest.dart");
 #import("dart:coreimpl");
 
 
-class SplayTreeTest {
+class SplayTreeMapTest {
 
   static testMain() {
-    SplayTree tree = new SplayTree();
+    SplayTreeMap tree = new SplayTreeMap();
     tree[1] = "first";
     tree[3] = "third";
     tree[5] = "fifth";
     tree[2] = "second";
     tree[4] = "fourth";
 
     var correctSolution = ["first", "second", "third", "fourth", "fifth"];
 
     tree.forEach((key, value) {
       Expect.equals(true, key >= 1);
       Expect.equals(true, key <= 5);
       Expect.equals(value, correctSolution[key - 1]);
     });
+
+    for (var v in ["first", "second", "third", "fourth", "fifth"]) {
+      Expect.isTrue(tree.containsValue(v));
+    };
+    Expect.isFalse(tree.containsValue("sixth"));
+
+    tree[7] = "seventh";
+
+    Expect.equals(1, tree.firstKey);
+    Expect.equals(7, tree.lastKey);
+
+    Expect.equals(2, tree.lastKeyBefore(3));
+    Expect.equals(4, tree.firstKeyAfter(3));
+
+    Expect.equals(null, tree.lastKeyBefore(1));
+    Expect.equals(2, tree.firstKeyAfter(1));
+
+    Expect.equals(4, tree.lastKeyBefore(5));
+    Expect.equals(7, tree.firstKeyAfter(5));
+
+    Expect.equals(5, tree.lastKeyBefore(7));
+    Expect.equals(null, tree.firstKeyAfter(7));
+
+    Expect.equals(5, tree.lastKeyBefore(6));
+    Expect.equals(7, tree.firstKeyAfter(6));
   }
 }
 
 main() {
-  SplayTreeTest.testMain();
+  SplayTreeMapTest.testMain();
 }