Remove most superfluous getter arguments from dart2js.

dart/lib/compiler/implementation/dart_backend/backend.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.
 
 class DartBackend extends Backend {
   final List<CompilerTask> tasks;
 
-  Map<Element, TreeElements> get resolvedElements() =>
+  Map<Element, TreeElements> get resolvedElements =>
       compiler.enqueuer.resolution.resolvedElements;
 
   DartBackend(Compiler compiler, [bool validateUnparse = false])
       : tasks = <CompilerTask>[],
       super(compiler);
 
   void enqueueHelpers(Enqueuer world) { }
   void codegen(WorkItem work) { }
   void processNativeClasses(Enqueuer world,
                             Collection<LibraryElement> libraries) { }
@@ skipping 172 matching lines @@
 
 List<Element> sortElements(Collection<Element> elements) {
   compareElements(e0, e1) {
     int result = compareBy((e) => e.getLibrary().uri.toString())(e0, e1);
     if (result != 0) return result;
     return compareBy((e) => e.position().charOffset)(e0, e1);
   }
 
   return sorted(elements, compareElements);
 }