[chromium] Remove unused WebRegularExpression API
https://bugs.webkit.org/show_bug.cgi?id=113520

Patch by James Robinson <jamesr@chromium.org> on 2013-03-28
Reviewed by Kent Tamura.

Last reference to these files removed in r190880.

* WebKit.gyp:
* public/WebRegularExpression.h: Removed.
* public/WebTextCaseSensitivity.h: Removed.
* src/AssertMatchingEnums.cpp:
* src/WebRegularExpression.cpp: Removed.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@147192 268f45cc-cd09-0410-ab3c-d52691b4dbfc