When building standalone Dart executable, put implementation of dart:io natives in a separate libra…

runtime/bin/io_impl_sources.gypi

Index: runtime/bin/io_impl_sources.gypi
diff --git a/runtime/bin/io_impl_sources.gypi b/runtime/bin/io_impl_sources.gypi
new file mode 100644
index 0000000000000000000000000000000000000000..bdc295047dd445e05be3673308b0b5602c57a9f4
--- /dev/null
+++ b/runtime/bin/io_impl_sources.gypi
@@ -0,0 +1,31 @@
+# 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 contains some C++ sources for the dart:io library.  The other
+# implementation files are in builtin_impl_sources.gypi.
+{
+  'sources': [
+    'eventhandler.cc',
+    'eventhandler.h',
+    'eventhandler_android.cc',
+    'eventhandler_linux.cc',
+    'eventhandler_linux.h',
+    'eventhandler_macos.cc',
+    'eventhandler_macos.h',
+    'eventhandler_win.cc',
+    'eventhandler_win.h',
+    'process.cc',
+    'process.h',
+    'process_android.cc',
+    'process_linux.cc',
+    'process_macos.cc',
+    'process_win.cc',
+    'socket.cc',
+    'socket.h',
+    'socket_android.cc',
+    'socket_linux.cc',
+    'socket_macos.cc',
+    'socket_win.cc',
+  ],
+}