Crash in initializeDb (Symbian)

A dynamic (down)-cast suddenly fails on a specific device. The pointer casted via dynamic_cast is 0 although other tests (TypeUid() == KCFbsFontUid) pass. It turns out that Rvct 2 does not officially support dynamic_cast, we apparently simply were lucky until now.

...crash!

20 Unknown (0x8033E47C)() 0x8033e47c
19 initializeDb() C:\dev\qt-qml\src\gui\text\qfontdatabase_s60.cpp:265 0x7ac34f6a
18 findFont() C:\dev\qt-qml\src\gui\text\qfontdatabase_s60.cpp:359 0x7ac36fb2
17 load() C:\dev\qt-qml\src\gui\text\qfontdatabase_s60.cpp:457 0x7ac37300
16 engineForScript() C:\dev\qt-qml\src\gui\text\qfont.cpp:271 0x7ac2e614
15 setDefaultHeight() C:\dev\qt-qml\src\gui\text\qtextengine.cpp:2013 0x7ac3d78c
14 layout_helper() C:\dev\qt-qml\src\gui\text\qtextlayout.cpp:1928 0x7ac41482
13 setNumColumns() C:\dev\qt-qml\src\gui\text\qtextlayout.cpp:1613 0x7ac41a58
12 endLayout() C:\dev\qt-qml\src\gui\text\qtextlayout.cpp:627 0x7ac41a86
11 updateDisplayText() C:\dev\qt-qml\src\gui\widgets\qlinecontrol.cpp:103 0x7ac9757e
10 init() C:\dev\qt-qml\src\corelib\tools\qstring.h:687 0x7ac994a2
9 QLineControl() C:\dev\qt-qml\src\gui\widgets\qlinecontrol_p.h:89 0x7acf5cba
8 init() C:\dev\qt-qml\src\gui\widgets\qlineedit_p.cpp:147 0x7ac94312
7 QLineEdit() C:\dev\qt-qml\src\gui\widgets\qlineedit.cpp:266 0x7ac95196
6 Dialog() C:\dev\qt-qml\examples\widgets\wiggly\dialog.cpp:52 0x7a2a860a
5 main() C:\dev\qt-qml\examples\widgets\wiggly\main.cpp:54 0x7a2a8802
4 QtMainWrapper() C:\dev\qt-qml\src\s60main\qts60main_mcrt0.cpp:86 0x7a2a89f8
3 E32Main() C:\dev\qt-qml\src\s60main\qts60main.cpp:56 0x7a2a8b50
2 CallThrdProcEntry() L:\src\cedar\generic\base\e32\compsupp\symaehabi\callfirstprocessfn.cpp:44 0x7a2a8ac0
1 RunThread() L:\src\cedar\generic\base\e32\euser\epoc\arm\uc_exe.cpp:61 0x7a2a899e