rewrite scope drop to be iterative

while I'm at it, remove the "extra caching" that I was doing for no good
reason except laziness. Basically before I was caching at each scope in
the chain, but there's not really a reason to do that, since the cached
entry point at level N is always equal to the last cached exit point
from level N-1.

0 files changed, 0 insertions, 0 deletions