Revert "Refactor Library/CompilationUnit and how we define local Scope."

tests/compiler/dart2js/find_my_name_test.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.
 
 #import("../../../lib/compiler/implementation/elements/elements.dart");
 #import("mock_compiler.dart");
 #import("parser_helper.dart");
 
 main() {
   MockCompiler compiler = new MockCompiler();
 
   String code = '''
 class Foo {
   operator+(other) => null;
 }
 ''';
 
   ClassElement foo = parseUnit(code, compiler, compiler.mainApp).head;
   foo.parseNode(compiler);
-  for (Element e in foo.localMembers) {
+  for (Element e in foo.localMembers.getValues()) {
     // TODO(ahe): Should test for e.name.slowToString() instead.
     Expect.equals(code.indexOf('operator+'), e.position().charOffset);
   }
 }