Check overrides.

dart/lib/compiler/implementation/closure.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("closureToClassMapper");
 
 #import("elements/elements.dart");
 #import("leg.dart");
 #import("scanner/scannerlib.dart");
 #import("tree/tree.dart");
@@ skipping 59 matching lines @@
     // We assign twice to [supertypeLoadState] as it contains asserts
     // which enforce certain sequence of transitions.
     supertypeLoadState = ClassElement.STATE_STARTED;
     supertypeLoadState = ClassElement.STATE_DONE;
     // Same as for [supertypeLoadState] above.
     resolutionState = ClassElement.STATE_STARTED;
     resolutionState = ClassElement.STATE_DONE;
     compiler.closureClass.ensureResolved(compiler);
     supertype = compiler.closureClass.computeType(compiler);
     interfaces = const EmptyLink<Type>();
+    allSupertypes = new Link<Type>(supertype);
   }
   bool isClosure() => true;
 }
 
 class BoxElement extends Element {
   BoxElement(SourceString name, Element enclosingElement)
       : super(name, ElementKind.VARIABLE, enclosingElement);
 }
 
 class ThisElement extends Element {
@@ skipping 414 matching lines @@
   }
 
   visitTryStatement(TryStatement node) {
     // TODO(ngeoffray): implement finer grain state.
     bool oldInTryStatement = inTryStatement;
     inTryStatement = true;
     node.visitChildren(this);
     inTryStatement = oldInTryStatement;
   }
 }