update test for file_field#set exception, and file_field#value=
update test for file_field#set exception, and file_field#value=

operasoftware/watir3-spec,watir/watirspec,titusfortner/watirspec,watir/watirspec,operasoftware/watir3-spec,titusfortner/watirspec,titusfortner/watirspec,watir/watirspec