[flutter_tools] add missing vm_service dep to BUILD.gn (#50454)

diff --git a/packages/flutter_tools/BUILD.gn b/packages/flutter_tools/BUILD.gn
index 9427c1f..c33e70e 100644
--- a/packages/flutter_tools/BUILD.gn
+++ b/packages/flutter_tools/BUILD.gn
@@ -46,6 +46,7 @@
     "//third_party/dart-pkg/pub/stack_trace",
     "//third_party/dart-pkg/pub/test",
     "//third_party/dart-pkg/pub/usage",
+    "//third_party/dart-pkg/pub/vm_service",
     "//third_party/dart-pkg/pub/web_socket_channel",
     "//third_party/dart-pkg/pub/webkit_inspection_protocol",
     "//third_party/dart-pkg/pub/xml",