Add the ability to get info of a Http connection, e.g. host and port.

tests/standalone/io/http_connection_info_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("dart:io");
+
+void testHttpConnectionInfo() {
+  HttpServer server = new HttpServer();
+  server.listen("0.0.0.0", 0);
+  int clientPort;
+  server.defaultRequestHandler = (HttpRequest request, HttpResponse response) {
+    Expect.isTrue(request.connectionInfo.remoteHost is String);
+    Expect.equals(request.connectionInfo.localPort, server.port);
+    Expect.isNotNull(clientPort);
+    Expect.equals(request.connectionInfo.remotePort, clientPort);
+    request.inputStream.onClosed = () {
+      response.outputStream.close();
+    };
+  };
+  server.onError = (Exception e) {
+    Expect.fail("Unexpected error: $e");
+  };
+
+
+  HttpClient client = new HttpClient();
+  HttpClientConnection conn = client.get("127.0.0.1", server.port, "/");
+  conn.onRequest = (HttpClientRequest request) {
+    Expect.isTrue(conn.connectionInfo.remoteHost is String);
+    Expect.equals(conn.connectionInfo.remotePort, server.port);
+    clientPort = conn.connectionInfo.localPort;
+    request.outputStream.close();
+  };
+  conn.onResponse = (HttpClientResponse response) {
+    response.inputStream.onClosed = () {
+      client.shutdown();
+      server.close();
+    };
+  };
+  conn.onError = (Exception e) {
+    Expect.fail("Unexpected error: $e");
+  };
+}
+
+void main() {
+  testHttpConnectionInfo();
+}