QWebView applications crash

For example, running qtwebkit-examples/examples/webkitwidgets/fancybrowser which tries to open the qt-project website. It renders initially, but soon crashes with the following backtrace:

ASSERTION FAILED: m_isCheckingArgumentTypes || m_canExit
/home/srodal/dev/qt5/qtwebkit/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp(110) : void JSC::DFG::SpeculativeJIT::backwardSpeculationCheck(JSC::ExitKind, JSC::DFG::JSValueSource, JSC::DFG::Node*, JSC::AbstractMacroAssembler<JSC::X86Assembler>::Jump)
1 0x7fddb72bc699 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(WTFCrash+0x1e) [0x7fddb72bc699]
2 0x7fddb70ab693 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1ee9693) [0x7fddb70ab693]
3 0x7fddb70ab982 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1ee9982) [0x7fddb70ab982]
4 0x7fddb70b8eb7 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1ef6eb7) [0x7fddb70b8eb7]
5 0x7fddb70e0a69 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1f1ea69) [0x7fddb70e0a69]
6 0x7fddb70b22a9 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1ef02a9) [0x7fddb70b22a9]
7 0x7fddb70b29ac /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1ef09ac) [0x7fddb70b29ac]
8 0x7fddb7082c92 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1ec0c92) [0x7fddb7082c92]
9 0x7fddb7083eb2 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1ec1eb2) [0x7fddb7083eb2]
10 0x7fddb707170a /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1eaf70a) [0x7fddb707170a]
11 0x7fddb7070f10 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1eaef10) [0x7fddb7070f10]
12 0x7fddb72001e8 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x203e1e8) [0x7fddb72001e8]
13 0x7fddb72004da /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x203e4da) [0x7fddb72004da]
14 0x7fddb71fe862 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x203c862) [0x7fddb71fe862]
15 0x7fddb71fe027 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x203c027) [0x7fddb71fe027]
16 0x7fddb6f66048 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1da4048) [0x7fddb6f66048]
17 0x7fddb6f61046 /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1d9f046) [0x7fddb6f61046]
18 0x7fddb714d3ea /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1f8b3ea) [0x7fddb714d3ea]
19 0x7fddb714a5bd /home/srodal/dev/qt5-debug/qtbase/lib/libQt5WebKit.so.5(+0x1f885bd) [0x7fddb714a5bd]
20 0x7fdd60bf8058 [0x7fdd60bf8058]
Segmentation fault (core dumped)

Reverting relatively recent change cf26dce826a7a6a2d14735c193c53b9103c4a369, "compileMakeRope does not emit necessary bounds checks" seems to fix it