Revert "Merge pull request #13149 from laurocaetano/fix_offset_last"

This reverts commit e18b2ca1289d08f76ff3e6ed09f1bf02ab8b7a04.

Reason: this change in behavior may cause some unexpected breakage in
applications relying on a stable version/branch, so we are leaving it
only on Rails master for now (which will be available with the 4.1 release).

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/test/cases/finder_test.rb
Improve AR changelog [ci skip]