Refactor and simplify the dart2dart renamer.

tests/compiler/dart2js/resolver_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 "package:expect/expect.dart";
 import 'dart:async';
 import "package:async_helper/async_helper.dart";
 import 'dart:collection';
 
 import "package:compiler/implementation/resolution/resolution.dart";
@@ skipping 591 matching lines @@
     Expect.equals(2, length(c.interfaces));
     Expect.equals(i1.computeType(compiler), at(c.interfaces, 0));
     Expect.equals(i2.computeType(compiler), at(c.interfaces, 1));
   });
 }
 
 Future testFunctionExpression() {
   return MockCompiler.create((MockCompiler compiler) {
     ResolverVisitor visitor = compiler.resolverVisitor();
     Map mapping = compiler.resolveStatement("int f() {}").map;
-    Expect.equals(1, mapping.length);
+    Expect.equals(2, mapping.length);
     Element element;
     Node node;
     mapping.forEach((Node n, Element e) {
       if (n is FunctionExpression) {
         element = e;
         node = n;
       }
     });
     Expect.equals(ElementKind.FUNCTION, element.kind);
     Expect.equals('f', element.name);
@@ skipping 441 matching lines @@
       }""";
   asyncTest(() => compileScript(script2).then((compiler) {
     expect(compiler,
         [MessageKind.CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS],
         [MessageKind.CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS_CONSTRUCTOR,
          MessageKind.CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS_CONSTRUCTOR,
          MessageKind.CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS_FIELD,
          MessageKind.CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS_FIELD]);
   }));
 }