Use the typedef arity to know how to invoke a closure given by the dom.

dart/lib/compiler/implementation/elements/elements.dart

Index: dart/lib/compiler/implementation/elements/elements.dart
===================================================================
--- dart/lib/compiler/implementation/elements/elements.dart	(revision 8049)
+++ dart/lib/compiler/implementation/elements/elements.dart	(working copy)
@@ -354,17 +354,29 @@
 }
 
 class TypedefElement extends Element {
-  final Token token;
   Type cachedType;
+  Typedef cachedNode;
 
-  TypedefElement(SourceString name, Element enclosing, this.token)
-      : super(name, ElementKind.TYPEDEF, enclosing) {
-    cachedType = new InterfaceType(this);
+  TypedefElement(SourceString name, Element enclosing)
+      : super(name, ElementKind.TYPEDEF, enclosing);
+
+  Type computeType(Compiler compiler) {

[ahe, 2012/05/29 13:21:50]

I'm absolutely 100% lukewarm on this approach. This looks like a copy of some
code I have seen in a different place.

+    if (cachedType !== null) return cachedType;
+    compiler.withCurrentElement(this, () {
+      FunctionSignature signature = compiler.resolveTypedef(this);
+      LinkBuilder<Type> parameterTypes = new LinkBuilder<Type>();
+      for (Link<Element> link = signature.requiredParameters;
+           !link.isEmpty();
+           link = link.tail) {
+         parameterTypes.addLast(link.head.computeType(compiler));
+         // TODO(karlklose): optional parameters.
+      }
+      cachedType = new FunctionType(compiler.types.dynamicType,
+                                    parameterTypes.toLink(),
+                                    this);
+    });
+    return cachedType;
   }
-
-  position() => findMyName(token);
-
-  Type computeType(Compiler compiler) => cachedType;
 }
 
 class VariableElement extends Element {