Debugger support for step-into async and async* functions.

runtime/vm/object_store.cc

Index: runtime/vm/object_store.cc
diff --git a/runtime/vm/object_store.cc b/runtime/vm/object_store.cc
index 27c92eb2608408974520af087326b82767156a03..475f19ce270cb5fd3e2f6885cdb5d30b3b6653f6 100644
--- a/runtime/vm/object_store.cc
+++ b/runtime/vm/object_store.cc
@@ -96,6 +96,7 @@ ObjectStore::ObjectStore()
       simple_instance_of_false_function_(Function::null()),
       async_clear_thread_stack_trace_(Function::null()),
       async_set_thread_stack_trace_(Function::null()),
+      async_star_move_next_helper_(Function::null()),
       library_load_error_table_(Array::null()),
       unique_dynamic_targets_(Array::null()),
       token_objects_(GrowableObjectArray::null()),
@@ -255,6 +256,13 @@ void ObjectStore::InitKnownObjects() {
   ASSERT(!function.IsNull());
   set_async_clear_thread_stack_trace(function);
 
+  function_name ^= async_lib.PrivateName(Symbols::AsyncStarMoveNextHelper());
+  ASSERT(!function_name.IsNull());
+  function ^= Resolver::ResolveStatic(async_lib, Object::null_string(),
+                                      function_name, 1, Object::null_array());
+  ASSERT(!function.IsNull());
+  set_async_star_move_next_helper(function);
+
   const Library& internal_lib = Library::Handle(_internal_library());
   cls = internal_lib.LookupClass(Symbols::Symbol());
   set_symbol_class(cls);