Async/await catch prediction for "the synchronous case"

src/debug/debug.cc

Index: src/debug/debug.cc
diff --git a/src/debug/debug.cc b/src/debug/debug.cc
index 747093e7492cb2119ee3d8008ef9492f713d56cf..b7a2f27a17d505f85f882925c6a58945a0c4b34e 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -1682,43 +1682,33 @@ void Debug::OnThrow(Handle<Object> exception) {
   }
 }
 
-
-void Debug::OnPromiseReject(Handle<JSObject> promise, Handle<Object> value) {
+void Debug::OnPromiseReject(Handle<Object> promise, Handle<Object> value) {
   if (in_debug_scope() || ignore_events()) return;
   HandleScope scope(isolate_);
   // Check whether the promise has been marked as having triggered a message.
   Handle<Symbol> key = isolate_->factory()->promise_debug_marker_symbol();
-  if (JSReceiver::GetDataProperty(promise, key)->IsUndefined(isolate_)) {
+  if (!promise->IsJSObject() ||
+      JSReceiver::GetDataProperty(Handle<JSObject>::cast(promise), key)
+          ->IsUndefined(isolate_)) {
     OnException(value, promise);
   }
 }
 
 
-MaybeHandle<Object> Debug::PromiseHasUserDefinedRejectHandler(
-    Handle<JSObject> promise) {
-  Handle<JSFunction> fun = isolate_->promise_has_user_defined_reject_handler();
-  return Execution::Call(isolate_, fun, promise, 0, NULL);
-}
-
-
 void Debug::OnException(Handle<Object> exception, Handle<Object> promise) {
   Isolate::CatchType catch_type = isolate_->PredictExceptionCatcher();
 
   // Don't notify listener of exceptions that are internal to a desugaring.
   if (catch_type == Isolate::CAUGHT_BY_DESUGARING) return;
 
-  bool uncaught = (catch_type == Isolate::NOT_CAUGHT);
+  bool uncaught = catch_type == Isolate::NOT_CAUGHT;
   if (promise->IsJSObject()) {
     Handle<JSObject> jspromise = Handle<JSObject>::cast(promise);
     // Mark the promise as already having triggered a message.
     Handle<Symbol> key = isolate_->factory()->promise_debug_marker_symbol();
     JSObject::SetProperty(jspromise, key, key, STRICT).Assert();
     // Check whether the promise reject is considered an uncaught exception.
-    Handle<Object> has_reject_handler;
-    ASSIGN_RETURN_ON_EXCEPTION_VALUE(
-        isolate_, has_reject_handler,
-        PromiseHasUserDefinedRejectHandler(jspromise), /* void */);
-    uncaught = has_reject_handler->IsFalse(isolate_);
+    uncaught = !isolate_->PromiseHasUserDefinedRejectHandler(jspromise);
   }
   // Bail out if exception breaks are not active
   if (uncaught) {