Added missing sync_socket_unsupported.cc and fixed issues in test which were causing analysis errors

tests/standalone/io/raw_synchronous_socket_test.dart

 // Copyright (c) 2017, 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:isolate";
 import "dart:math";
 
 import "package:async_helper/async_helper.dart";
 import "package:expect/expect.dart";
 
 const String LOOPBACK_IP_V4_STRING = "127.0.0.1";
 
 void testArguments() {
   Expect.throws(() => RawSynchronousSocket.connectSync(null, 0));
   Expect.throws(
       () => RawSynchronousSocket.connectSync(LOOPBACK_IP_V4_STRING, null));
   Expect.throws(
       () => RawSynchronousSocket.connectSync(LOOPBACK_IP_V4_STRING, 65536));
   Expect.throws(
       () => RawSynchronousSocket.connectSync(LOOPBACK_IP_V4_STRING, -1));
-  Expect.throws(() =>
-      RawSynchronousSocket.connectSync(LOOPBACK_IP_V4_STRING, 0, backlog: -1));
 }
 
 // The connection attempt happens on the main Dart thread and the OS timeout can
 // be arbitrarily long, causing timeout issues on the build bots. This isn't an
 // issue with the async sockets since the lookup for a connect call happens on
 // the IO service thread.
 /*
 void testInvalidConnect() {
   // Connect to an unknown DNS name.
   try {
@@ skipping 147 matching lines @@
       }, onDone: () {
         Expect.isTrue(closedEventReceived);
         connections++;
         if (connections >= connection_count) {
           server.close();
         }
       });
     }, onDone: () {
       // Let the client know we're shutting down then kill the isolate.
       sendPort.send(null);
-      kill();
+      Isolate.current.kill();
     });
   });
 }
 
 Future testSimpleReadWrite({bool dropReads}) async {
   asyncStart();
   // This test creates a server and a client connects. The client writes data
   // to the socket and the server echos it back. The client confirms the data it
   // reads is the same as the data sent, then closes the socket, resulting in
   // the closing of the server, which responds on receivePort with null to
@@ skipping 281 matching lines @@
   await testShutdown();
   testSimpleConnect();
   testServerListenAfterConnect();
   await testSimpleReadWrite();
   await testPartialRead();
   await testPartialWrite();
   testInvalidReadWriteOperations();
   testClosedError();
   asyncEnd();
 }