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

utils/compiler/BUILD.gn

Index: utils/compiler/BUILD.gn
diff --git a/utils/compiler/BUILD.gn b/utils/compiler/BUILD.gn
index 8d64954be8acd70fac30b3fd22a9bac2c6a62ac1..52645050d69aebecc2e07d593f1f066c1fdff2be 100644
--- a/utils/compiler/BUILD.gn
+++ b/utils/compiler/BUILD.gn
@@ -6,24 +6,28 @@ 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",