Support top-level field declaration and assignment in analyzer2dart.

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 '../util/util.dart';
 import 'cps_ir_nodes.dart';
 
 /// A [Decorator] is a function used by [SExpressionStringifier] to augment the
@@ skipping 27 matching lines @@
     String name = node.element.name;
     namer.useReturnName(node.returnContinuation);
     String parameters = node.parameters.map(visit).join(' ');
     String body = indentBlock(() => visit(node.body));
     return '$indentation(FunctionDefinition $name ($parameters return)\n'
            '$body)';
   }
 
   String visitFieldDefinition(FieldDefinition node) {
     String name = node.element.name;
-    namer.useReturnName(node.returnContinuation);
-    String body = indentBlock(() => visit(node.body));
-    return '$indentation(FieldDefinition $name (return)\n'
-           '$body)';
+    if (node.hasInitializer) {
+      namer.useReturnName(node.returnContinuation);
+      String body = indentBlock(() => visit(node.body));
+      return '$indentation(FieldDefinition $name (return)\n'
+             '$body)';
+    } else {
+      return '$indentation(FieldDefinition $name)';
+    }
   }
 
   String visitLetPrim(LetPrim node) {
     String name = newValueName(node.primitive);
     String value = visit(node.primitive);
     String body = visit(node.body);
     return '$indentation(LetPrim $name $value)\n$body';
   }
 
   String visitLetCont(LetCont node) {
@@ skipping 174 matching lines @@
   String useReturnName(Continuation node) {
     assert(!_names.containsKey(node) || _names[node] == 'return');
     return _names[node] = 'return';
   }
 
   String getName(Node node) {
     assert(_names.containsKey(node));
     return _names[node];
   }
 }