dart2js: Refactoring, documentation, and a few bugfixes in Namer class.

pkg/compiler/lib/src/js_backend/codegen/codegen.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.
 
 library code_generator;
 
 import 'glue.dart';
 
 import '../../tree_ir/tree_ir_nodes.dart' as tree_ir;
 import '../../js/js.dart' as js;
@@ skipping 252 matching lines @@
     List<js.Expression> arguments = visitArguments(node.arguments);
     return buildStaticInvoke(selector, target, arguments);
   }
 
   @override
   js.Expression visitInvokeMethodDirectly(tree_ir.InvokeMethodDirectly node) {
     registry.registerDirectInvocation(node.target.declaration);
     if (node.target is ConstructorBodyElement) {
       // A constructor body cannot be overriden or intercepted, so we can
       // use the short form for this invocation.
-      // TODO(asgerf): prevent name clash between constructor bodies.
       return js.js('#.#(#)',
           [visitExpression(node.receiver),
            glue.instanceMethodName(node.target),
            visitArguments(node.arguments)]);
     }
     return js.js('#.#.call(#, #)',
         [glue.prototypeAccess(node.target.enclosingClass),
          glue.invocationName(node.selector),
          visitExpression(node.receiver),
          visitArguments(node.arguments)]);
@@ skipping 245 matching lines @@
 
   @override
   visitSuperInitializer(tree_ir.SuperInitializer node) {
     return errorUnsupportedNode(node);
   }
 
   dynamic errorUnsupportedNode(tree_ir.DartSpecificNode node) {
     throw "Unsupported node in JS backend: $node";
   }
 }