Fix for issue 19817

runtime/bin/dartutils.cc

Index: runtime/bin/dartutils.cc
===================================================================
--- runtime/bin/dartutils.cc	(revision 38470)
+++ runtime/bin/dartutils.cc	(working copy)
@@ -799,6 +799,12 @@
   Dart_Handle async_lib = Dart_LookupLibrary(url);
   DART_CHECK_VALID(async_lib);
   Dart_Handle io_lib = Builtin::LoadAndCheckLibrary(Builtin::kIOLibrary);
+
+  // We need to ensure that all the scripts loaded so far are finalized
+  // as we are about to invoke some Dart code below to setup closures.
+  result = Dart_FinalizeLoading(false);
+  DART_CHECK_VALID(result);
+
   Dart_Handle timer_closure =
       Dart_Invoke(io_lib, NewString("_getTimerFactoryClosure"), 0, NULL);
   Dart_Handle args[1];