XWayland crash when drag&drop link

Hi,

I am running Firefox-esr on Debian Buster.

$ firefox-esr --version
Mozilla Firefox 60.2.2

$ uname -a
Linux JEJE 4.18.0-1-amd64 #1 SMP Debian 4.18.6-1 (2018-09-06) x86_64 GNU/Linux

$ gnome-shell --version
GNOME Shell 3.30.0

With some internet sites, when I begin to drag and drop a link within Firefox it makes gnome crash. Then gdm reboots at the login screen.

Finally I get a ~100MB file in my user home directory called core

Reproducibility 100%

How to reproduce:

• Navigate to: https://moodle.univ-tlse3.fr/
• Resize the Firefox window on the right (or left) side of your screen
• Try to drag&drop the link "Presentation Moodle"

Gnome should crash and produce a core file

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I don't know if it is related but on regular sites drag&drop a link in nautilus no longer creates a link to the website in the current directory and make firefox totally unresponsive to mouse or keyboard events.