Dart: Performance improvements to Dart's handle watcher.

mojo/dart/embedder/BUILD.gn

Index: mojo/dart/embedder/BUILD.gn
diff --git a/mojo/dart/embedder/BUILD.gn b/mojo/dart/embedder/BUILD.gn
index 1789f6e78d0a1d73123b2072a14ace88d1548f88..a3572c0b18ae3957899095d5397d1d5d1302b3b4 100644
--- a/mojo/dart/embedder/BUILD.gn
+++ b/mojo/dart/embedder/BUILD.gn
@@ -122,6 +122,7 @@ action_foreach("dart_embedder_package_sdk") {
     "//mojo/public/dart/mojo/sdk_ext/src/handle_watcher.dart",
     "//mojo/public/dart/mojo/sdk_ext/src/natives.dart",
     "//mojo/public/dart/mojo/sdk_ext/src/timer_queue.dart",
+    "//mojo/public/dart/mojo/sdk_ext/src/wait_many_state.dart",
   ]
   outputs = [
     "$root_gen_dir/dart_embedder_packages/{{source_root_relative_dir}}/{{source_file_part}}",
@@ -303,6 +304,7 @@ action("generate_snapshot_bin") {
     "//mojo/public/dart/mojo/sdk_ext/src/handle_watcher.dart",
     "//mojo/public/dart/mojo/sdk_ext/src/natives.dart",
     "//mojo/public/dart/mojo/sdk_ext/src/timer_queue.dart",
+    "//mojo/public/dart/mojo/sdk_ext/src/wait_many_state.dart",
   ]
   vm_isolate_snapshot = "$target_gen_dir/vm_isolate_snapshot.bin"
   isolate_snapshot = "$target_gen_dir/isolate_snapshot.bin"