Qt application crashes trying to execute QTextDocument::setHtml() with special text

I found a crash in KDE which is described in this report: https://bugs.kde.org/show_bug.cgi?id=284718
It appears when an application (reproduced with several ones) tries to call methods that lead to QTextDocument::setHtml() call (e.g. setText to QTextEdit) with special text. The text is equal to the body of this tweet: http://twitter.com/#!/tiesto/status/127767987531948032 being received to a QString. For instance, KWin crashes when browser try to compose window title using the tweet.

Backtrace for KWin is attached.