[debug] Disable debug events if JS execution is disallowed

src/debug/debug.cc

Index: src/debug/debug.cc
diff --git a/src/debug/debug.cc b/src/debug/debug.cc
index 6564726830609bc65d9ade701c8f3ba007064ff9..cb1f34f390e50b54eab226359e504ec39ca10c7b 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -1777,6 +1777,11 @@ void Debug::OnPromiseReject(Handle<Object> promise, Handle<Object> value) {
 
 
 void Debug::OnException(Handle<Object> exception, Handle<Object> promise) {
+  // We cannot generate debug events when JS execution is disallowed.
+  // TODO(5530): Reenable debug events within DisallowJSScopes once relevant
+  // code (MakeExceptionEvent and ProcessDebugEvent) have been moved to C++.
+  if (!AllowJavascriptExecution::IsAllowed(isolate_)) return;
+
   Isolate::CatchType catch_type = isolate_->PredictExceptionCatcher();
 
   // Don't notify listener of exceptions that are internal to a desugaring.