Fix some cases where Map.containsValue did not accept Object as argument.

sdk/lib/_internal/js_runtime/lib/constant_map.dart

Index: sdk/lib/_internal/js_runtime/lib/constant_map.dart
diff --git a/sdk/lib/_internal/js_runtime/lib/constant_map.dart b/sdk/lib/_internal/js_runtime/lib/constant_map.dart
index 8f813fc6615d2ae952c3d12eabe2ebafccf2f834..8a6a5c9d930370a3151b5d52ea9fd7058a6cbd1d 100644
--- a/sdk/lib/_internal/js_runtime/lib/constant_map.dart
+++ b/sdk/lib/_internal/js_runtime/lib/constant_map.dart
@@ -75,7 +75,7 @@ class ConstantStringMap<K, V> extends ConstantMap<K, V> {
   final _jsObject;
   final List<K> _keys;
 
-  bool containsValue(V needle) {
+  bool containsValue(Object needle) {
     return values.any((V value) => value == needle);
   }
 
@@ -160,7 +160,7 @@ class GeneralConstantMap<K, V> extends ConstantMap<K, V> {
     return backingMap;
   }
 
-  bool containsValue(V needle) {
+  bool containsValue(Object needle) {
     return _getMap().containsValue(needle);
   }