Bug 1693859

Description of problem:
If running under GNOME Shell under Wayland, and Firefox is also running in Wayland mode (firefox-wayland), an attempt to repeatedly paste a long text into any unconstrained text input control (input type=text) will eventually crash Firefox with a SIGSEGV. The crash does NOT happen if Firefox is started in the default X11 mode, even under GNOME Shell on Wayland.

Version-Release number of selected component (if applicable):
firefox-66.0.1-1.fc29.x86_64
firefox-wayland-66.0.1-1.fc29.x86_64


How reproducible:
Always

Steps to Reproduce:
1. Start GNOME Shell using Wayland (the default in Fedora 29). Other wayland compositors have not been tested.
2. Install, then run firefox-wayland
3. Open any web page with a text input control that does not have any maximum length specified
4. Focus on the input control, then press any letter key to get a long string of characters
5. Select the entirety of this character string and copy it to the clipboard
6. Focus on the input control, and keep Ctrl-V pressed to paste the long string at high speed

Actual results:
Firefox segfaults and terminates

Expected results:
No segfault. Firefox should either keep accepting characters in the input control, or block the paste attempts on whathever limit is appropriate.

Additional info:

ABRT points me to this report, but I do not know if it is the right one:
https://retrace.fedoraproject.org/faf/reports/2507322/