[infra] Translate _sources.gypi files to _sources.gni files

runtime/lib/internal_sources.gni

Index: runtime/lib/internal_sources.gni
diff --git a/runtime/lib/internal_sources.gni b/runtime/lib/internal_sources.gni
new file mode 100644
index 0000000000000000000000000000000000000000..61c4e1543758f95e5437f9693e1d8206bd4acc41
--- /dev/null
+++ b/runtime/lib/internal_sources.gni
@@ -0,0 +1,14 @@
+# Copyright (c) 2017, 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.
+
+# Sources that patch the library "dart:_internal".
+internal_runtime_sources = [
+  "internal_patch.dart",
+
+  # The above file needs to be first as it imports required libraries.
+  "class_id.dart",
+  "class_id.cc",
+  "print_patch.dart",
+  "symbol_patch.dart",
+]