Revert "Removed SecurityContext.alpnSupported, as ALPN is now supported on all platforms. Also upda…

runtime/bin/secure_socket_patch.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.
 
 @patch
 class SecureSocket {
   @patch
   factory SecureSocket._(RawSecureSocket rawSocket) =>
       new _SecureSocket(rawSocket);
 }
@@ skipping 111 matching lines @@
 class SecurityContext {
   @patch
   factory SecurityContext() {
     return new _SecurityContext();
   }
 
   @patch
   static SecurityContext get defaultContext {
     return _SecurityContext.defaultContext;
   }
+
+  @patch
+  static bool get alpnSupported => true;
 }
 
 class _SecurityContext extends NativeFieldWrapperClass1
     implements SecurityContext {
   _SecurityContext() {
     _createNativeContext();
   }
 
   void _createNativeContext() native "SecurityContext_Allocate";
 
@@ skipping 60 matching lines @@
         isUtc: true);
   }
 
   DateTime get endValidity {
     return new DateTime.fromMillisecondsSinceEpoch(_endValidity(), isUtc: true);
   }
 
   int _startValidity() native "X509_StartValidity";
   int _endValidity() native "X509_EndValidity";
 }