Realize that this() is a closure send.

sdk/lib/_internal/compiler/implementation/elements/elements.dart

 // Copyright (c) 2012, 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 elements;
 
 import 'dart:uri';
 
 import 'modelx.dart';
 import '../tree/tree.dart';
@@ skipping 303 matching lines @@
 
   static bool isInstanceSend(Send send, TreeElements elements) {
     Element element = elements[send];
     if (element == null) return !isClosureSend(send, element);
     return isInstanceMethod(element) || isInstanceField(element);
   }
 
   static bool isClosureSend(Send send, Element element) {
     if (send.isPropertyAccess) return false;
     if (send.receiver != null) return false;
+    Node selector = send.selector;
+    // this().
+    if (selector.isThis()) return true;
     // (o)() or foo()().
-    if (element == null && send.selector.asIdentifier() == null) return true;
+    if (element == null && selector.asIdentifier() == null) return true;
     if (element == null) return false;
     // foo() with foo a local or a parameter.
     return isLocal(element);
   }
 
   static SourceString constructConstructorName(SourceString receiver,
                                                SourceString selector) {
     String r = receiver.slowToString();
     String s = selector.slowToString();
     return new SourceString('$r\$$s');
@@ skipping 522 matching lines @@
   int get resolutionState;
   Token get beginToken;
   Token get endToken;
 
   // TODO(kasperl): Try to get rid of these.
   void set annotatedElement(Element value);
   void set resolutionState(int value);
 
   MetadataAnnotation ensureResolved(Compiler compiler);
 }