Fix `first(limit)` to take advantage of `loaded?` records if available

I realized that `first(2)`, etc. was unnecessarily querying for the
records when they were already preloaded. This was because
`find_nth_with_limit` can not know which `@records` to return because
it conflates the `offset` and `index` into a single variable, while
the `@records` only needs the `index` itself to select the proper
record.

Because `find_nth` and `find_nth_with_limit` are public methods, I
instead introduced a private method `find_nth_with_limit_and_offset`
which is called internally and handles the `loaded?` checking.

Once the `offset` argument is removed from `find_nth`,
`find_nth_with_limit_and_offset` can be collapsed into
`find_nth_with_limit`, with `offset` always equal to `offset_index`.

0 files changed, 0 insertions, 0 deletions