Can not find Element in Dynamic element.

compiler/java/com/google/dart/compiler/resolver/Elements.java

 // Copyright (c) 2011, 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.
 
 package com.google.dart.compiler.resolver;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.dart.compiler.ast.DartClass;
 import com.google.dart.compiler.ast.DartField;
 import com.google.dart.compiler.ast.DartFunctionExpression;
@@ skipping 93 matching lines @@
     } else {
       throw new IllegalArgumentException();
     }
   }
 
   public static void addParameter(MethodElement method, VariableElement parameter) {
     ((MethodElementImplementation) method).addParameter(parameter);
   }
 
   static Element findElement(ClassElement cls, String name) {
-    return ((ClassElementImplementation) cls).findElement(name);
+    if (cls instanceof ClassElementImplementation) {

[zundel, 2011/10/24 15:07:44]

I think rather than an instanceof test, the preferred way to handle this is to
find ElementKind.of(cls).  You'll want to test for ElementKind.CLASS.  I think
possibly a FUNCION_ALIAS might be passed in sometimes which you would want to
filter out.

[scheglov, 2011/10/24 19:57:55]

I'm not sure.
At first, we cast to this type, so it is just logical to test using instanceof.
At second, we would need to test not only for CLASS, but also for
FUNCTION_TYPE_ALIAS.

+      return ((ClassElementImplementation) cls).findElement(name);
+    }
+    return null;
   }
 
   public static MethodElement methodFromFunctionExpression(DartFunctionExpression node,
                                                            Modifiers modifiers) {
     return MethodElementImplementation.fromFunctionExpression(node, modifiers);
   }
 
   static MethodElement methodFromMethodNode(DartMethodDefinition node, EnclosingElement holder) {
     return MethodElementImplementation.fromMethodNode(node, holder);
   }
@@ skipping 85 matching lines @@
     return VoidElement.getInstance();
   }
 
   /**
    * Returns true if the class needs an implicit default constructor.
    */
   public static boolean needsImplicitDefaultConstructor(ClassElement classElement) {
     return !classElement.isObject() && classElement.getConstructors().isEmpty();
   }
 }