We should move from cost String& to String/String&& in the constructor/getter.
Didn’t notice you had filed this bug. I fixed this as part of merging with your changes in <https://trac.webkit.org/changeset/206960>. We can use this bug to finish up in case there are any loose ends.
There is probably nothing to do here. Closing bug.
<rdar://problem/34995871>