Refactor and simplify the dart2dart renamer.

sdk/lib/_internal/compiler/implementation/resolution/registry.dart

 // Copyright (c) 2014, 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.
 
 part of resolution;
 
 /// [ResolutionRegistry] collects all resolution information. It stores node
 /// related information in a [TreeElements] mapping and registers calls with
 /// [Backend], [World] and [Enqueuer].
 // TODO(johnniwinther): Split this into an interface and implementation class.
@@ skipping 13 matching lines @@
   World get universe => compiler.world;
 
   Backend get backend => compiler.backend;
 
   //////////////////////////////////////////////////////////////////////////////
   //  Node-to-Element mapping functionality.
   //////////////////////////////////////////////////////////////////////////////
 
   /// Register [node] as the declaration of [element].
   void defineFunction(FunctionExpression node, FunctionElement element) {
+    // TODO(sigurdm): Remove when not needed by the dart2dart backend.
+    if (node.name != null) {
+      mapping[node.name] = element;
+    }
     mapping[node] = element;
   }
 
   /// Register [node] as a reference to [element].
   Element useElement(Node node, Element element) {
     if (element == null) return null;
     return mapping[node] = element;
   }
 
   /// Register [node] as the declaration of [element].
@@ skipping 310 matching lines @@
 
   void registerAssert(Send node) {
     mapping.setAssert(node);
     backend.resolutionCallbacks.onAssert(node, this);
   }
 
   bool isAssert(Send node) {
     return mapping.isAssert(node);
   }
 }