rwldrn/jquery — comment on commit 18cd11047625232d3b88d0183c14f525d296a371
File: src/ajax.js line 821
By dmethvin:

This isn't likely to be a perf-critical path, so isPlainObject alone would be shorter. Also, all other constructed non-plain objects (e.g., Date) will now be stringified in param() by encodeURIComponent, dunno if that changes their behavior as well.