Remove unused include of RegularExpression.h
https://bugs.webkit.org/show_bug.cgi?id=113649

Reviewed by Dimitri Glazkov.

* Modules/filesystem/DOMFilePath.cpp:
    - This include isn't used.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@147284 268f45cc-cd09-0410-ab3c-d52691b4dbfc