Clean up some of the fn3 debugging logic. (#6024)
Clean up some of the fn3 debugging logic. (#6024)

The debugging logic was lagging behind the recent actual logic changes,
especially around buildScope.
Hixie/flutter,tvolkert/flutter,flutter/flutter,tvolkert/flutter,flutter/flutter,tvolkert/flutter,turnidge/flutter,flutter/flutter,tvolkert/flutter,Hixie/flutter,tvolkert/flutter,cbracken/flutter,tvolkert/flutter,Hixie/flutter,turnidge/flutter,tvolkert/flutter,cbracken/flutter,cbracken/flutter,turnidge/flutter,flutter/flutter,cbracken/flutter,Hixie/flutter,cbracken/flutter,Hixie/flutter,flutter/flutter,flutter/flutter,tvolkert/flutter,tvolkert/flutter,Hixie/flutter,flutter/flutter,cbracken/flutter,Hixie/flutter,flutter/flutter,cbracken/flutter,tvolkert/flutter,Hixie/flutter,flutter/flutter,cbracken/flutter,Hixie/flutter,turnidge/flutter,Hixie/flutter,cbracken/flutter,turnidge/flutter,cbracken/flutter,flutter/flutter