Second step towards loading the core library scripts directly from the sources

runtime/lib/libgen_in.cc

Index: runtime/lib/libgen_in.cc
===================================================================
--- runtime/lib/libgen_in.cc	(revision 0)
+++ runtime/lib/libgen_in.cc	(revision 0)
@@ -0,0 +1,13 @@
+// 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
+};