HarfBuzz related crash at phoronix.com

For some reason users of Otter Browser get this backtrace (99% chances to reproduce it) when visiting http://phoronix.com.

Program received signal SIGSEGV, Segmentation fault.
(gdb) bt
#0 0x00007ffff3b8378b in ?? () from /opt/Qt/5.3/gcc_64/lib/libQt5Gui.so.5
#1 0x00007ffff347c44a in ?? () from /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5
#2 0x00007ffff347de70 in ?? () from /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5
#3 0x00007ffff3b87444 in QFontEngine::harfbuzzFont() const () from /opt/Qt/5.3/gcc_64/lib/libQt5Gui.so.5
#4 0x00007ffff3baaae2 in QTextEngine::shapeTextWithHarfbuzz(QScriptItem const&, unsigned short const*, int, QFontEngine*, QVector<unsigned int> const&, bool) const () from /opt/Qt/5.3/gcc_64/lib/libQt5Gui.so.5
#5 0x00007ffff3bab402 in QTextEngine::shapeText(int) const () from /opt/Qt/5.3/gcc_64/lib/libQt5Gui.so.5
#6 0x00007ffff3babd80 in QTextEngine::shape(int) const () from /opt/Qt/5.3/gcc_64/lib/libQt5Gui.so.5
#7 0x00007ffff3bbd6fb in QTextLine::layout_helper(int) () from /opt/Qt/5.3/gcc_64/lib/libQt5Gui.so.5
#8 0x00007ffff3bbe97d in QTextLine::setLineWidth(double) () from /opt/Qt/5.3/gcc_64/lib/libQt5Gui.so.5
#9 0x00007ffff5c5da75 in ?? () from /opt/Qt/5.3/gcc_64/lib/libQt5WebKit.so.5
#10 0x00007ffff5c5f6e1 in ?? () from /opt/Qt/5.3/gcc_64/lib/libQt5WebKit.so.5
#11 0x00007ffff5c3edc1 in ?? () from /opt/Qt/5.3/gcc_64/lib/libQt5WebKit.so.5
#12 0x00007ffff683e16a in ?? () from /opt/Qt/5.3/gcc_64/lib/libQt5WebKit.so.5

For some reason I cannot reproduce it using demobrowser from examples and cannot reproduce that at all using Qt 5.2.1 (SDK).

Original bug report:
https://github.com/Emdek/otter/issues/308