Add support for fields to the new dart backend.

pkg/compiler/lib/src/tree_ir/tree_ir_tracer.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 tree_ir_tracer;
 
 import 'dart:async' show EventSink;
 import '../tracer.dart';
 import 'tree_ir_nodes.dart';
 
@@ skipping 32 matching lines @@
   }
   void _addGotoStatement(Block target) {
     blocks.last.statements.add(target);
   }
 
   void _addBlock(Block block) {
     block.index = blocks.length;
     blocks.add(block);
   }
 
-  void collect(FunctionDefinition function) {
-    visitStatement(function.body);
+  void collect(ExecutableDefinition node) {
+    visitStatement(node.body);
   }
 
   visitLabeledStatement(LabeledStatement node) {
     Block target = new Block(node.label);
     breakTargets[node.label] = target;
     visitStatement(node.body);
     _addBlock(target);
     visitStatement(node.next);
   }
 
@@ skipping 79 matching lines @@
 
 class TreeTracer extends TracerUtil with StatementVisitor {
   final EventSink<String> output;
 
   TreeTracer(this.output);
 
   Names names;
   BlockCollector collector;
   int statementCounter;
 
-  void traceGraph(String name, FunctionDefinition function) {
+  void traceGraph(String name, ExecutableDefinition node) {
     names = new Names();
     statementCounter = 0;
     collector = new BlockCollector();
-    collector.collect(function);
+    collector.collect(node);
     tag("cfg", () {
       printProperty("name", name);
       int blockCounter = 0;
       collector.blocks.forEach(printBlock);
     });
     names = null;
   }
 
   void printBlock(Block block) {
     tag("block", () {
@@ skipping 242 matching lines @@
       String prefix = v.element == null ? 'v' : '${v.element.name}_';
       while (name == null || _usedNames.contains(name)) {
         name = "$prefix${_counter++}";
       }
       _names[v] = name;
       _usedNames.add(name);
     }
     return name;
   }
 }