Fix external exceptions in external try-catch handlers.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 7a761b68a5e1a86c618ed02bbc6bde1ac674922f..57809ce4f9b598116641fabb1947a685956458f7 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -1062,9 +1062,12 @@ void Isolate::ScheduleThrow(Object* exception) {
   // When scheduling a throw we first throw the exception to get the
   // error reporting if it is uncaught before rescheduling it.
   Throw(exception);
-  thread_local_top()->scheduled_exception_ = pending_exception();
-  thread_local_top()->external_caught_exception_ = false;
-  clear_pending_exception();
+  PropagatePendingExceptionToExternalTryCatch();
+  if (has_pending_exception()) {
+    thread_local_top()->scheduled_exception_ = pending_exception();
+    thread_local_top()->external_caught_exception_ = false;
+    clear_pending_exception();
+  }
 }