[esnext] prototype runtime implementation for async functions

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 926b9866d4e019afb8fad2dd811f876e20044449..b445c49cdc856a55507ecd729a41de3a503d8476 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -336,6 +336,7 @@ static bool IsVisibleInStackTrace(JSFunction* fun,
   if (!FLAG_builtins_in_stack_traces && fun->shared()->IsBuiltin()) {
     return fun->shared()->native();
   }
+
   return true;
 }