[Wayland] Browser crash when clicking textarea containing >= 4076 bytes

I have compiled the Otter browser against Qt5 (branch 5.4) @ a68a6b964f770fef3ea3d52f29d0c7a86186e80c. Otter crashes reproducibly when clicking inside a textarea filled with at least 4076 bytes, leaving a message like this in the terminal:
Data too big for buffer (4100 > 4096)

It was suspected that the bug is in QtWebKit, please see the report for Otter:
https://github.com/Emdek/otter/issues/608

The command I'm running is:
otter-browser -platform wayland

The program crashes with SIGABRT.

I'm using the standard wayland packages from opensuse 13.2, versions:
libwayland-client0: 1.6.0-1.1
libwayland-cursor0: 1.6.0-1.1
libwayland-server0: 1.6.0-1.1
wayland-devel: 1.6.0-1.1
libwayland-egl1: 10.3.0-91.3.2
libwayland-egl-devel: 10.3.0-91.3.2