Description of problem: Attempting to copy/paste from X11 apps like Chromium, Hexchat into Wayland apps like GNOME Terminal fails.

Version-Release number of selected component (if applicable):
xorg-x11-server-Xwayland-1.20.5-7.fc31.x86_64
chromium-77.0.3865.90-2.fc31.x86_64
chromium-vaapi-77.0.3865.90-1.fc31.x86_64
hexchat-2.14.2-5.fc31.x86_64
gnome-terminal-3.34.1-1.fc31.x86_64

How reproducible:
Reproducible

Steps to Reproduce:
In a GNOME/Wayland session, with middle-click pasting enabled:
1. Select text in a Chromium window.
2. Middle-click into a terminal window.

Or, in a GNOME/Wayland session:
1. Select text in a Chromium window.
2. Press Ctrl+C to copy it.
3. Switch to a terminal window.
4. Press Ctrl+V to paste.

Actual results:
The selected text is not pasted.

Expected results:
The selected/copied text is pasted, this works in GNOME/Xorg, as well as between X11 apps under Wayland.

Additional info:
Copy/paste via Ctrl+C/V works from Hexchat to Wayland apps like the Terminal, but not from Chromium or xterm (with Shift+Ctrl+C/V bound to copy/paste to/from clipboard).