Update roadmap.

Author: ayjayt

ROADMAP.md

@@ -1,5 +1,7 @@
 # Roadmap
 
+- [ ] What happens to the underlying task when we cancel a future in a
+  `protocol.devtools_async_helpers` timeout situation?
 - [ ] Extract local download check to chromium implementation class
 - [x] Fix up browser deps error (eliminate in-package analysis)
 - [x] Switch to process group and kill that to catch all chromium children