This switches over to using `LookupForAdd` which allows us to avoid a second lookup when adding the entry. Addtionally `nsDependentCString` is used to avoid copying the id string when looking up the entry.
This switches over to using `LookupForAdd` which allows us to avoid a second lookup when adding the entry. Addtionally `nsDependentCString` is used to avoid copying the id string when looking up the entry.