Dart: Reorganize files

mojo/dart/embedder/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # embedder specific template rules.
 import("embedder.gni")
 import("//mojo/dart/packages/mojo/sources.gni")
 import("//mojo/dart/packages/mojo/sdk_ext_sources.gni")
 
+group("embedder") {
+  deps = [
+    ":dart_controller_no_snapshot",
+    ":generate_snapshot_file",
+    "//mojo/dart/embedder/snapshotter",
+  ]
+}
+
 source_set("dart_controller_no_snapshot") {
   sources = [
     "$target_gen_dir/dart_embedder_patch_resources.cc",
     "$target_gen_dir/dart_embedder_service_isolate_resources.cc",
     "builtin.cc",
     "builtin.h",
     "builtin_natives.cc",
     "common.cc",
     "common.h",
     "dart_controller.cc",
@@ skipping 230 matching lines @@
 
 source_set("dart_snapshot_cc") {
   sources = [
     "$root_gen_dir/dart_snapshot.cc",
   ]
 
   deps = [
     ":generate_snapshot_file",
   ]
 }