Fix doctest failure in #drag_and_drop_by.
Fix doctest failure in #drag_and_drop_by.

titusfortner/watir,jkotests/watir,jkotests/watir,watir/watir,titusfortner/watir,titusfortner/watir-webdriver,jkotests/watir,watir/watir,jkotests/watir-webdriver,jkotests/watir-webdriver,watir/watir,titusfortner/watir,watir/watir,titusfortner/watir,titusfortner/watir-webdriver,jkotests/watir