Parse formal parameters.

dart/frog/leg/tree/nodes.dart

Index: dart/frog/leg/tree/nodes.dart
diff --git a/dart/frog/leg/tree/nodes.dart b/dart/frog/leg/tree/nodes.dart
index daf8b26d94e6fb90d25e4df9326c50942ae13c16..e882b2e33473fbc76545449cb2c410bd08334100 100644
--- a/dart/frog/leg/tree/nodes.dart
+++ b/dart/frog/leg/tree/nodes.dart
@@ -14,7 +14,6 @@ interface Visitor<R> {
   R visitLiteralString(LiteralString node);
   R visitNodeList(NodeList node);
   R visitOperator(Operator node);
-  R visitParameter(Parameter node);
   R visitReturn(Return node);
   R visitSend(Send node);
   R visitSendSet(SendSet node);
@@ -313,21 +312,6 @@ class Operator extends Identifier {
   accept(Visitor visitor) => visitor.visitOperator(this);
 }
 
-class Parameter extends Node {
-  final Identifier name;
-  final TypeAnnotation typeAnnotation;
-
-  const Parameter(this.name, [this.typeAnnotation]);
-
-  accept(Visitor visitor) => visitor.visitParameter(this);
-
-  Token getBeginToken() {
-    return firstBeginToken(typeAnnotation, name);
-  }
-
-  Token getEndToken() => name.getEndToken();
-}
-
 class Return extends Statement {
   final Expression expression;
   final Token beginToken;