Fuchsia: Enable newly working socket tests; use MX_CLOCK_UTC.

runtime/tests/vm/dart/hello_fuchsia_test.dart

 // Copyright (c) 2016, 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";
 
 testAddressParse() async {
   print(new InternetAddress("1.0.2.3").rawAddress);
   print(new InternetAddress("1.0.2.3").type);
@@ skipping 379 matching lines @@
   print("testSimpleBind done");
 
   print("testSimpleConnect");
   await testSimpleConnect();
   print("testSimpleConnect done");
 
   print("testSimpleReadWriteClose");
   await testSimpleReadWriteClose();
   print("testSimpleReadWriteClose done");
 
-  // TODO(US-81): Enable.
-  // print("testSimpleReadWriteShutdown");
-  // await testSimpleReadWriteShutdown(dropReads: false);
-  // print("testSimpleReadWriteShutdown done");
+  print("testSimpleReadWriteShutdown");
+  await testSimpleReadWriteShutdown(dropReads: false);
+  print("testSimpleReadWriteShutdown done");
 
   print("testGoogleHttp");
   await testGoogleHttp(null, 'pass');
   print("testGoogleHttp done");
 
-  // TODO(US-96)
-  // print("testGoogleHttps");
-  // await testGoogleHttps(null, 'pass');
-  // print("testGoogleHttps done");
+  print("testGoogleHttps");
+  await testGoogleHttps(null, 'pass');
+  print("testGoogleHttps done");
 
   print("Goodbyte, Fuchsia!");
 }