Currently, our various LRB entry points are a mess, and quite inefficient too.
- We have three entry points, one is checking for null, and calls a non-null version, but that checks for null again
- We don't have to check for null at all: it can be subsumed in the cset-check
- The LRB resolves forwardee even though has_forwarded_objects() and in_cset() has not been checked
- The LRB entry is not inlineable