Add built-in root certificates to dart:io SecureSocket.

runtime/tools/gyp/nss_configurations.gypi

 # 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 included to modify the configurations to build third-party
 # code from Mozilla's NSS and NSPR libraries, modified by the Chromium project.
 # This code is C code, not C++, and is not warning-free, so we need to remove
 # C++-specific flags, and add flags to supress the warnings in the code.
 # This file is included from gyp files in the runtime/bin/net directory.
 {
   'variables': {
     # Used by third_party/nss, which is from Chromium.
-    # When the NSS and related libraries gyp files are processed in
-    # Dartium, do not override the settings from Dartium.  The targets will
-    # not be built.
+    # Include the built-in set of root certificate authorities.
+    'exclude_nss_root_certs': 0,
     'os_posix%': 1,
     'os_bsd%': 0,
     'chromeos%': 0,
     'clang%': 0,
   },
   'target_defaults': {
     'cflags': [
       '-Wno-unused-variable',
       '-Wno-unused-but-set-variable',
       '-Wno-missing-field-initializers',
@@ skipping 40 matching lines @@
       'Dart_Release': {
         'xcode_settings': {
           # Remove 'ansi' setting.
           'GCC_C_LANGUAGE_STANDARD': 'c99',
           'GCC_TREAT_WARNINGS_AS_ERRORS': 'NO', # -Werror off
         },
       },
     },
   },
 }