Parse formal parameters.

dart/frog/leg/typechecker.dart

 // Copyright (c) 2011, 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.
 
 class TypeCheckerTask extends CompilerTask {
   TypeCheckerTask(Compiler compiler) : super(compiler);
   String get name() => "Type checker";
 
   void check(Node tree, Map<Node, Element> elements) {
     measure(() {
@@ skipping 201 matching lines @@
   Type visitNodeList(NodeList node) {
     for (Link<Node> link = node.nodes; !link.isEmpty(); link = link.tail) {
       type(link.head);
     }
   }
 
   Type visitOperator(Operator node) {
     return types.dynamicType;
   }
 
-  Type visitParameter(Parameter node) {
-    return null;
-  }
-
   checkAssignable(Node node, Type s, Type t) {
     if (!types.isAssignable(s, t)) {
       var error = CompilerError.notAssignable(s, t);
       compiler.reportWarning(node, error);
     }
   }
 
   Type visitReturn(Return node) {
     Type expressionType = type(node.expression);
     checkAssignable(node, expectedReturnType, expressionType);
@@ skipping 18 matching lines @@
          link = link.tail) {
       Node initialization = link.head;
       if (initialization is Send) {
         checkAssignable(node, type, nonVoidType(link.head));
       } else if (initialization is !Identifier) {
         compiler.cancel('unexpected node type for variable initialization');
       }
     }
   }
 }