[Qt] QWebSettings::clearMemoryCaches should release FastMalloc's free pages to OS
https://bugs.webkit.org/show_bug.cgi?id=111605

Patch by Arunprasad Rajkumar <arunprasadr@nds.com> on 2013-03-08
Reviewed by Jocelyn Turcotte.

* Api/qwebsettings.cpp:
(QWebSettings::clearMemoryCaches):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@145211 268f45cc-cd09-0410-ab3c-d52691b4dbfc