Refactor SharedFunctionInfo::IsBuiltin.

src/accessors.cc

Index: src/accessors.cc
diff --git a/src/accessors.cc b/src/accessors.cc
index 7f45f404c45dbcc680636d49453559b8639cf077..de84a7f2b153bf87d0d326b5867b91aebfafe68e 100644
--- a/src/accessors.cc
+++ b/src/accessors.cc
@@ -1024,10 +1024,11 @@ MaybeHandle<JSFunction> FindCaller(Isolate* isolate,
     if (caller == NULL) return MaybeHandle<JSFunction>();
   } while (caller->shared()->is_toplevel());
 
-  // If caller is a built-in function and caller's caller is also built-in,
+  // If caller is not user code and caller's caller is also not user code,
   // use that instead.
   JSFunction* potential_caller = caller;
-  while (potential_caller != NULL && potential_caller->shared()->IsBuiltin()) {
+  while (potential_caller != NULL &&
+         !potential_caller->shared()->IsUserJavaScript()) {
     caller = potential_caller;
     potential_caller = it.next();
   }