[promises] cleanup default promise handlers

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/isolate.h"
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
@@ skipping 1860 matching lines @@
 
   if (queue->IsUndefined(isolate)) {
     return false;
   }
 
   if (queue->IsCallable()) {
     return PromiseHandlerCheck(isolate, Handle<JSReceiver>::cast(queue),
                                Handle<JSReceiver>::cast(deferred_promise));
   }
 
+  if (queue->IsSymbol()) {
+    return InternalPromiseHasUserDefinedRejectHandler(
+        isolate, Handle<JSPromise>::cast(deferred_promise));
+  }
+
   Handle<FixedArray> queue_arr = Handle<FixedArray>::cast(queue);
   Handle<FixedArray> deferred_promise_arr =
       Handle<FixedArray>::cast(deferred_promise);
   for (int i = 0; i < deferred_promise_arr->length(); i++) {
     Handle<JSReceiver> queue_item(JSReceiver::cast(queue_arr->get(i)));
     Handle<JSReceiver> deferred_promise_item(
         JSReceiver::cast(deferred_promise_arr->get(i)));
     if (PromiseHandlerCheck(isolate, queue_item, deferred_promise_item)) {
       return true;
     }
@@ skipping 1766 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8