Update version of NSS in Dart to 3.16.7

dart/runtime/bin/net/nss.gyp

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # 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.
 
 # This file is a modified copy of Chromium's deps/third_party/nss/nss.gyp.
 # Revision 291806 (this should agree with "nss_rev" in DEPS).
@@ skipping 1062 matching lines @@
         '<(nss_directory)/nss/lib/util/nssrwlk.h',
         '<(nss_directory)/nss/lib/util/nssrwlkt.h',
         '<(nss_directory)/nss/lib/util/nssutil.h',
         '<(nss_directory)/nss/lib/util/oidstring.c',
         '<(nss_directory)/nss/lib/util/pkcs11.h',
         '<(nss_directory)/nss/lib/util/pkcs11f.h',
         '<(nss_directory)/nss/lib/util/pkcs11n.h',
         '<(nss_directory)/nss/lib/util/pkcs11p.h',
         '<(nss_directory)/nss/lib/util/pkcs11t.h',
         '<(nss_directory)/nss/lib/util/pkcs11u.h',
+        '<(nss_directory)/nss/lib/util/pkcs1sig.c',
+        '<(nss_directory)/nss/lib/util/pkcs1sig.h',
         '<(nss_directory)/nss/lib/util/portreg.c',
         '<(nss_directory)/nss/lib/util/portreg.h',
         '<(nss_directory)/nss/lib/util/quickder.c',
         '<(nss_directory)/nss/lib/util/secalgid.c',
         '<(nss_directory)/nss/lib/util/secasn1.h',
         '<(nss_directory)/nss/lib/util/secasn1d.c',
         '<(nss_directory)/nss/lib/util/secasn1e.c',
         '<(nss_directory)/nss/lib/util/secasn1t.h',
         '<(nss_directory)/nss/lib/util/secasn1u.c',
         '<(nss_directory)/nss/lib/util/seccomon.h',
@@ skipping 296 matching lines @@
             'os_windows.c',
             # mpi_x86_asm.c contains MSVC inline assembly code.
             '<(nss_directory)/nss/lib/freebl/mpi/mpi_x86_asm.c',
           ],
         }],
       ],
     },
   ],
   }]],
 }