Overhaul tree IR visitor and rename IR classes.

pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.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 dart2js.ir_nodes_sexpr;
 
 import '../constants/values.dart';
 import '../util/util.dart';
 import 'cps_ir_nodes.dart';
 
@@ skipping 44 matching lines @@
     String thisParameter = formatThisParameter(node.thisParameter);
     String parameters = node.parameters.map(visit).join(' ');
     String body = visit(node.body);
     return '$indentation'
         '(FunctionDefinition $name $thisParameter ($parameters) return\n'
         '$body)';
   }
 
   String visitFieldDefinition(FieldDefinition node) {
     String name = node.element.name;
-    if (node.hasInitializer) {
+    if (node.body != null) {
       String body = visit(node.body);
       return '$indentation(FieldDefinition $name () return\n'
              '$body)';
     } else {
       return '$indentation(FieldDefinition $name)';
     }
   }
 
   String visitConstructorDefinition(ConstructorDefinition node) {
     String name = node.element.name;
@@ skipping 28 matching lines @@
 
   String visitSuperInitializer(SuperInitializer node) {
     String target = node.target.name;
     String selector = node.selector.name;
     String arguments =
         indentBlock(() =>
           indentBlock(() => node.arguments.map(visit).join('\n')));
     return '$indentation(SuperInitializer $target $selector (\n$arguments)';
   }
 
-  String visitRunnableBody(RunnableBody node) {
+  String visitBody(Body node) {
     namer.setReturnContinuation(node.returnContinuation);
     return indentBlock(() => visit(node.body));
   }
 
   String visitLetPrim(LetPrim node) {
     String name = newValueName(node.primitive);
     String value = visit(node.primitive);
     String body = indentBlock(() => visit(node.body));
     return '$indentation(LetPrim ($name $value)\n$body)';
   }
@@ skipping 342 matching lines @@
   void setReturnContinuation(Continuation node) {
     assert(!_names.containsKey(node) || _names[node] == 'return');
     _names[node] = 'return';
   }
 
   String getName(Node node) {
     assert(_names.containsKey(node));
     return _names[node];
   }
 }