Fix datagram issue where available is not correctly updated upon receive.

tests/standalone/io/raw_datagram_read_all_test.dart

Index: tests/standalone/io/raw_datagram_read_all_test.dart
diff --git a/tests/standalone/io/raw_datagram_read_all_test.dart b/tests/standalone/io/raw_datagram_read_all_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..67eef8b3c009aa66f2de8308e0138355c9cb3504
--- /dev/null
+++ b/tests/standalone/io/raw_datagram_read_all_test.dart
@@ -0,0 +1,42 @@
+// Copyright (c) 2014, 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:async";
+import "dart:io";
+import "dart:typed_data";
+
+import "package:async_helper/async_helper.dart";
+import "package:expect/expect.dart";
+
+
+main() {
+  asyncStart();
+  var address = InternetAddress.LOOPBACK_IP_V4;
+  RawDatagramSocket.bind(address, 0).then((producer) {
+    RawDatagramSocket.bind(address, 0).then((receiver) {
+      int sent = 0;
+      new Timer.periodic(const Duration(microseconds: 1), (timer) {
+        producer.send([0], address, receiver.port);
+        sent++;
+        if (sent == 100) {
+          timer.cancel();
+          producer.close();
+        }
+      });
+      var timer;
+      receiver.listen((event) {
+        if (event != RawSocketEvent.READ) return;
+        var datagram = receiver.receive();
+        Expect.listEquals([0], datagram.data);
+        if (timer != null) timer.cancel();
+        timer = new Timer(const Duration(milliseconds: 200), () {
+          Expect.isNull(receiver.receive());
+          receiver.close();
+          asyncEnd();
+        });
+      });
+    });
+  });
+}
+