Use entities in the TypeMask interface.

pkg/compiler/lib/src/universe/world_builder.dart

 // 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.
 
 library universe;
 
 import 'dart:collection';
 
 import '../cache_strategy.dart';
 import '../common.dart';
@@ skipping 63 matching lines @@
   ///     class A {
   ///        foo(a, b) {}
   ///     }
   ///     class B {
   ///        foo(a, b) {}
   ///     }
   ///     new A().foo(a, b);
   ///
   /// Ideally the selector constraints for calls `foo` with two positional
   /// arguments apply to `A.foo` but `B.foo`.
-  bool applies(Element element, Selector selector, World world);
+  bool applies(MemberElement element, Selector selector, World world);
 
   /// Returns `true` if at least one of the receivers matching these constraints
   /// in the closed [world] have no implementation matching [selector].
   ///
   /// For instance for this code snippet
   ///
   ///     class A {}
   ///     class B { foo() {} }
   ///     m(b) => (b ? new A() : new B()).foo();
   ///
@@ skipping 1871 matching lines @@
   @override
   EnumSet<MemberUse> get _originalUse => MemberUses.ALL_STATIC;
 }
 
 void removeFromSet(Map<String, Set<_MemberUsage>> map, Element element) {
   Set<_MemberUsage> set = map[element.name];
   if (set == null) return;
   set.removeAll(
       set.where((_MemberUsage usage) => usage.entity == element).toList());
 }