Implement super initializers.

frog/leg/typechecker.dart

Index: frog/leg/typechecker.dart
diff --git a/frog/leg/typechecker.dart b/frog/leg/typechecker.dart
index d4575baa42176dc0a8073cae854a3fe70e78dff5..6f694f1cc41776ee046f0aef94b47b7f954f2fa3 100644
--- a/frog/leg/typechecker.dart
+++ b/frog/leg/typechecker.dart
@@ -238,9 +238,19 @@ class TypeCheckerVisitor implements Visitor<Type> {
   }
 
   Type visitFunctionExpression(FunctionExpression node) {
+    Type type;
+    Type returnType;
+    Type previousType;
     final FunctionElement element = elements[node];
-    FunctionType functionType = computeType(element);
-    Type returnType = functionType.returnType;
+    if (element.kind === ElementKind.GENERATIVE_CONSTRUCTOR ||
+        element.kind === ElementKind.GENERATIVE_CONSTRUCTOR_BODY) {
+      type = types.dynamicType;
+      returnType = types.voidType;
+    } else {
+      FunctionType functionType = computeType(element);
+      returnType = functionType.returnType;
+      type = functionType;
+    }
     Type previous = expectedReturnType;
     expectedReturnType = returnType;
     if (element.isMember()) currentClass = element.enclosingElement;
@@ -256,7 +266,7 @@ class TypeCheckerVisitor implements Visitor<Type> {
       reportTypeWarning(node.name, kind);
     }
     expectedReturnType = previous;
-    return functionType;
+    return type;
   }
 
   Type visitIdentifier(Identifier node) {