Javascripts fails on big-endian systems

In debian the test qtbug46548_overriddenProperties fails for all big-endian fails:
https://buildd.debian.org/status/package.php?p=qtwebchannel-opensource-src

The traceback shows a bug deep inside QV4:
Thread 1 (Thread 0xf7d48dd0 (LWP 16526)):
#0 0x0f203f38 in waitpid () from /lib/powerpc-linux-gnu/libc.so.6
No symbol table info available.
#1 0x0f189990 in ?? () from /lib/powerpc-linux-gnu/libc.so.6
No symbol table info available.
#2 0x0fb1aa38 in ?? () from /usr/lib/powerpc-linux-gnu/libQt5Test.so.5
No symbol table info available.
#3 0x0fb1ab7c in ?? () from /usr/lib/powerpc-linux-gnu/libQt5Test.so.5
No symbol table info available.
#4 <signal handler called>
No symbol table info available.
#5 0x0fd01e18 in QV4::ExecutionContext::getFunctionObject() const ()
from /usr/lib/powerpc-linux-gnu/libQt5Qml.so.5
No symbol table info available.
#6 0x0fcf73e8 in QV4::ExecutionEngine::stackTrace(int) const ()
from /usr/lib/powerpc-linux-gnu/libQt5Qml.so.5
No symbol table info available.
#7 0x0fd2c634 in ?? () from /usr/lib/powerpc-linux-gnu/libQt5Qml.so.5
No symbol table info available.
[...]

full traceback see https://bugs.debian.org/836412