- Include sources in gen_snapshot and dart_no_snapshot to allow

runtime/lib/libgen_in.cc

 // Copyright (c) 2013, 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.
 
 #include "{{INCLUDE}}" // NOLINT
 
 // This file is used to generate the mapping of libraries which have
 // dart:<name> handles to the corresponding files that implement them.
 const char* {{VAR_NAME}}[] = {
 {{LIBRARY_SOURCE_MAP}}
 {{PART_SOURCE_MAP}}
-  NULL, NULL
+  NULL, NULL, NULL
 };