Allow assignment to `range` field
Allow assignment to `range` field

This guarantees full backwards compatibility for clients which reassign
`range` during the iteration (e.g. atom/find-and-replace)

pombredanne/text-buffer,jacekkopecky/text-buffer,jacekkopecky/text-buffer,atom/text-buffer,whodatninja/text-buffer,atom/text-buffer,pombredanne/text-buffer