Use list_dart_files.py instead of list_files.py in GN build.

utils/compiler/BUILD.gn

 # Copyright (c) 2016, 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.
 
 import("../create_timestamp.gni")
 import("../invoke_dart.gni")
 
 create_timestamp_file("dart2js_files_stamp") {
-  pattern = "\\.dart\$"
   path = rebase_path("../../pkg/compiler/lib")
   output = "$root_gen_dir/dart2js_files.stamp"
 }
 
+create_timestamp_file("runtime_lib_files_stamp") {
+  path = rebase_path("../../runtime/lib")
+  output = "$target_gen_dir/runtime_lib_files.stamp"
+}
+
+create_timestamp_file("dartdoc_files_stamp") {
+  path = rebase_path("../../sdk/lib/_internal/dartdoc")
+  output = "$target_gen_dir/dartdoc_files.stamp"
+}
+
 invoke_dart("dart2js") {
   deps = [
     ":dart2js_files_stamp",
+    ":runtime_lib_files_stamp",
+    ":dartdoc_files_stamp",
   ]
 
-  dart_files = exec_script("../../tools/list_files.py",
-                          ["\\.dart\$",
-                           rebase_path("../../runtime/lib"),
-                           rebase_path("../../sdk/lib/_internal/dartdoc")],
-                          "list lines")
-
-  inputs = dart_files + [
-    "../../tools/list_files.py",
+  inputs = [
     "../../sdk/lib/_internal/sdk_library_metadata/lib/libraries.dart",
     "create_snapshot.dart",
     "$root_gen_dir/dart2js_files.stamp",
     "../../tools/VERSION",
   ]
 
   utils_output = "$root_gen_dir/utils_wrapper.dart.snapshot"
   dart2js_output = "$root_gen_dir/dart2js.dart.snapshot"
   outputs = [
     utils_output,
     dart2js_output,
   ]
 
   dot_packages = rebase_path("../../.packages")
   create_snapshot = rebase_path("create_snapshot.dart")
   output_dir = rebase_path(root_gen_dir)
 
   args = [
     "--packages=$dot_packages",
     create_snapshot,
     "--output_dir=$output_dir",
     "--dart2js_main=pkg/compiler/lib/src/dart2js.dart",
   ]
 }