Second round of cleanups for new optional parameter semantics.

tests/standalone/io/http_shutdown_test.dart

Index: tests/standalone/io/http_shutdown_test.dart
===================================================================
--- tests/standalone/io/http_shutdown_test.dart	(revision 13754)
+++ tests/standalone/io/http_shutdown_test.dart	(working copy)
@@ -9,7 +9,7 @@
 void test1(int totalConnections) {
   // Server which just closes immediately.
   HttpServer server = new HttpServer();
-  server.listen("127.0.0.1", 0, totalConnections);
+  server.listen("127.0.0.1", 0, backlog: totalConnections);
   server.defaultRequestHandler = (HttpRequest request, HttpResponse response) {
     response.outputStream.close();
   };
@@ -35,7 +35,7 @@
 void test2(int totalConnections) {
   // Server which responds without waiting for request body.
   HttpServer server = new HttpServer();
-  server.listen("127.0.0.1", 0, totalConnections);
+  server.listen("127.0.0.1", 0, backlog: totalConnections);
   server.defaultRequestHandler = (HttpRequest request, HttpResponse response) {
     response.outputStream.writeString("!dlrow ,olleH");
     response.outputStream.close();
@@ -64,7 +64,7 @@
 void test3(int totalConnections) {
   // Server which responds when request body has been received.
   HttpServer server = new HttpServer();
-  server.listen("127.0.0.1", 0, totalConnections);
+  server.listen("127.0.0.1", 0, backlog: totalConnections);
   server.defaultRequestHandler = (HttpRequest request, HttpResponse response) {
     request.inputStream.onData = () {
       request.inputStream.read();