After r80892 there are over 100,000 leaks reported on the leaks bot. Prior to that revision the number was much, much smaller.
Created attachment 85668 [details]
The explicit calls to StringImpl::ref seem as though they will also result in leaks as there are no matching calls to StringImpl::deref anywhere. The patch removes those as well as fixing the bigger issue of the leaked duplicate entries.
Fixed in r81051.