Change core lib, dart2js, and more for new optional parameters syntax

tests/compiler/dart2js/unparser2_test.dart

 // Copyright (c) 2012, 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.
 
 #import("../../../lib/compiler/implementation/scanner/scannerlib.dart");
 #import("../../../lib/compiler/implementation/elements/elements.dart"); // only need CompilationUnitElement
 #import("../../../lib/compiler/implementation/tree/tree.dart");
 #import("../../../lib/compiler/implementation/leg.dart"); // only need DiagnosticListener & Script
 
 main() {
@@ skipping 46 matching lines @@
   Node node = listener.popNode();
   Expect.isTrue(listener.nodes.isEmpty());
   return unparse(node);
 }
 
 class MessageCollector implements DiagnosticListener {
   List<String> messages;
   MessageCollector() {
     messages = [];
   }
-  void cancel([String reason, node, token, instruction, element]) {
+  void cancel(String reason, {node, token, instruction, element}) {
     messages.add(reason);
     throw reason;
   }
   void log(message) {
     messages.add(message);
   }
   void internalErrorOnElement(Element element, String message) {
     throw message;
   }
   void internalError(String message,
-                     [Node node, Token token, dynamic instruction,
-                      Element element]) {
+                     {Node node, Token token, dynamic instruction,
+                      Element element}) {
     throw message;
   }
 }