[Qt] memory leak in WebCore::FontCache::getLastResortFallbackFont

https://bugs.webkit.org/show_bug.cgi?id=118532

Patch by Fabienne Semeria <fsemeria@nds.com> on 2013-07-11
Reviewed by Allan Sandfeld Jensen.

* platform/graphics/qt/FontCacheQt.cpp:
(WebCore::FontCache::getLastResortFallbackFont):

Change-Id: Ic647594b3d6eaaeb036a3d3d88f2eb533cffedb7
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@152563 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Reviewed-by: Fabienne Semeria <fsemeria@nds.com>
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>