Dir.children is available since Feature #11302.
Find.find can use of the new list (having no '.' neither '..' entries),
making now superflous an if statement.

This change can improve the performance of Find.find when the path
has lots of entries (thousands?).

https://bugs.ruby-lang.org/issues/11302
patched by Espartaco Palma <esparta@gmail.com>
https://github.com/ruby/ruby/pull/1697 fix GH-1697
[Feature #13896]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59926 b2dd03c8-39d4-4d8f-98ff-823fe69b080e