Fixed some static type warnings in vm core libraries

runtime/lib/immutable_map.dart

Index: runtime/lib/immutable_map.dart
diff --git a/runtime/lib/immutable_map.dart b/runtime/lib/immutable_map.dart
index 1b762732981b0a42942f378e31a018e561a0f93b..689a931eb3d75941a75bdfd0b22d31526cc12238 100644
--- a/runtime/lib/immutable_map.dart
+++ b/runtime/lib/immutable_map.dart
@@ -46,7 +46,7 @@ class ImmutableMap<K, V> implements Map<K, V> {
 
   Collection<V> getValues() {
     int numValues = length;
-    List<K> list = new List<K>(numValues);
+    List<V> list = new List<V>(numValues);
     for (int i = 0; i < numValues; i++) {
       list[i] = kvPairs_[i*2 + 1];
     }