ruby/ruby — pull request #743 by suzukaze (2014-10-20 12:03:32+00:00)
Title: Fix document of Kernel.Stirng

Kernel#String tries not `to_s` but `to_str` first.

The follwing source:
rb_String(VALUE val)
https://github.com/ruby/ruby/blob/trunk/object.c#L3010

rb_check_string_type
https://github.com/ruby/ruby/blob/trunk/string.c#L1745