classes with call-methods were not recognized as Functions.

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 '../tree/tree.dart';
 import '../util/util.dart';
 import '../resolution/resolution.dart';
@@ skipping 889 matching lines @@
   void set supertype(DartType value);
   void set interfaces(Link<DartType> value);
   void set patch(ClassElement value);
   void set origin(ClassElement value);
   void set supertypeLoadState(int value);
   void set resolutionState(int value);
   void set nativeTagInfo(String value);
 
   bool isObject(Compiler compiler);
   bool isSubclassOf(ClassElement cls);
+  /// Returns true if `this` exlicitly/nominally implements [intrface].

[Johnni Winther, 2014/02/03 08:27:25]

'exlicitly' -> 'explicitly'

[floitsch, 2014/02/03 17:43:20]

Done.

+  ///
+  /// Note that, if [intrface] is the `Function` class, this method returns
+  /// falso for a class that has a `call` method but does not explicitly
+  /// implement `Function`.
   bool implementsInterface(ClassElement intrface);
   bool hasFieldShadowedBy(Element fieldMember);
 
   /// Returns `true` if this class has a @proxy annotation.
   bool get isProxy;
 
   /// Returns `true` if the class hierarchy for this class contains errors.
   bool get hasIncompleteHierarchy;
 
   ClassElement ensureResolved(Compiler compiler);
@@ skipping 179 matching lines @@
   InterfaceType get declarer;
 
   /// Returns `true` if this member is static.
   bool get isStatic;
 
   /// Returns `true` if this member is a getter or setter implicitly declared
   /// by a field.
   bool get isDeclaredByField;
 }