Introduce the TYPEDEF element, and use it in order to catch passing closures to the DOM. I make the…

frog/leg/resolver.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.
 
 interface TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
 }
 
 class TreeElementMapping implements TreeElements {
@@ skipping 593 matching lines @@
     }
     if (className == const SourceString('var')) return null;
     if (className == const SourceString('void')) return null;
     Element element = context.lookup(className);
     if (element === null) {
       if (typeRequired) {
         error(node, MessageKind.CANNOT_RESOLVE_TYPE, [className]);
       } else {
         warning(node, MessageKind.CANNOT_RESOLVE_TYPE, [className]);
       }
-    } else if (element.kind !== ElementKind.CLASS) {
+    } else if (!element.isClassOrInterfaceOrAlias()) {
       if (typeRequired) {
         error(node, MessageKind.NOT_A_TYPE, [className]);
       } else {
         warning(node, MessageKind.NOT_A_TYPE, [className]);
       }
     } else {
-      ClassElement cls = element;
-      compiler.resolver.toResolve.add(element);
+      if (element.isClass()) {
+        // TODO(ngeoffray): Should we also resolve typedef?
+        ClassElement cls = element;
+        compiler.resolver.toResolve.add(element);
+      }
       // TODO(ahe): This should be a Type.
       useElement(node, element);
     }
     return element;
   }
 
   Element defineElement(Node node, Element element,
                         [bool doAddToScope = true]) {
     compiler.ensure(element !== null);
     mapping[node] = element;
@@ skipping 591 matching lines @@
     if (name === null) {
       unimplemented(node.typeName, "prefixes");
     }
     return visit(name);
   }
 
   Type visitIdentifier(Identifier node) {
     Element element = context.lookup(node.source);
     if (element === null) {
       error(node, MessageKind.CANNOT_RESOLVE_TYPE, [node]);
-    } else if (element.kind !== ElementKind.CLASS) {
+    } else if (!element.isClassOrInterfaceOrAlias()) {
       error(node, MessageKind.NOT_A_TYPE, [node]);
     } else {
       compiler.resolver.toResolve.add(element);
       // TODO(ngeoffray): Use type variables.
       return element.computeType(compiler);
     }
     return null;
   }
 }
 
@@ skipping 233 matching lines @@
 class TopScope extends Scope {
   LibraryElement get library() => element;
 
   TopScope(LibraryElement library) : super(null, library);
   Element lookup(SourceString name) => library.find(name);
 
   Element add(Element element) {
     throw "Cannot add an element in the top scope";
   }
 }