additional SDK fixes. This gets all of them, once we upgrade to new analyzer

tool/input_sdk/lib/collection/splay_tree.dart

Index: tool/input_sdk/lib/collection/splay_tree.dart
diff --git a/tool/input_sdk/lib/collection/splay_tree.dart b/tool/input_sdk/lib/collection/splay_tree.dart
index 112698b98b7ebcf3f3659ec4afdbef4f2721969d..d932933201edaa2842d0cf3e909cbf525d15d61e 100644
--- a/tool/input_sdk/lib/collection/splay_tree.dart
+++ b/tool/input_sdk/lib/collection/splay_tree.dart
@@ -66,6 +66,10 @@ abstract class _SplayTree<K> {
   /** Comparison used to compare keys. */
   int _compare(K key1, K key2);
 
+  Comparator<K> get _comparator;
+
+  _Predicate<Object> get _validKey;
+
   /**
    * Perform the splay operation for the given key. Moves the node with
    * the given key to the top of the tree.  If no node has the given