Further reduce use of Element in codegen.

pkg/compiler/lib/src/js_backend/namer.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.
 
 library js_backend.namer;
 
 import 'dart:collection' show HashMap;
 
 import 'package:js_runtime/shared/embedded_names.dart' show JsGetName;
 
@@ skipping 1351 matching lines @@
   ///
   /// Example translation to JS:
   ///
   ///     A.prototype.super$A$foo = function() {...}
   ///     A.prototype.foo$0 = A.prototype.super$A$foo
   ///
   ///     B.prototype.foo$0 = function() {
   ///         this.super$A$foo(); // super.foo()
   ///     }
   ///
-  jsAst.Name aliasedSuperMemberPropertyName(Element member) {
+  jsAst.Name aliasedSuperMemberPropertyName(MemberElement member) {
     assert(!member.isField); // Fields do not need super aliases.
     return _disambiguateInternalMember(member, () {
       String invocationName = operatorNameToIdentifier(member.name);
       return "super\$${member.enclosingClass.name}\$$invocationName";
     });
   }
 
   /// Property name in which to store the given static or instance [method].
   /// For instance methods, this includes the suffix encoding arity and named
   /// parameters.
@@ skipping 712 matching lines @@
   void addSuggestion(String original, String suggestion) {
     assert(!_suggestedNames.containsKey(original));
     _suggestedNames[original] = suggestion;
   }
 
   bool hasSuggestion(String original) => _suggestedNames.containsKey(original);
   bool isSuggestion(String candidate) {
     return _suggestedNames.containsValue(candidate);
   }
 }