Implement named constructors and resolving of redirecting constructors and super-initializers.

frog/leg/scanner/listener.dart

Index: frog/leg/scanner/listener.dart
diff --git a/frog/leg/scanner/listener.dart b/frog/leg/scanner/listener.dart
index 02d631076812265e29d36894352a8bf5d16107e1..655d1c8a27bce107cab69b0d014c714ab95d039f 100644
--- a/frog/leg/scanner/listener.dart
+++ b/frog/leg/scanner/listener.dart
@@ -860,7 +860,8 @@ class NodeListener extends ElementListener {
     Statement body = popNode();
     NodeList initializers = popNode();
     NodeList formals = popNode();
-    Identifier name = popNode();
+    // The name can be an identifier or a send in case of named constructors.
+    Expression name = popNode();
     TypeAnnotation type = popNode();
     Modifiers modifiers = popNode();
     pushNode(new FunctionExpression(name, formals, body, type,