RequestPolicy crushes Firefox when you scroll up and down a long menu of blocked destinations using the mouse wheel

[SCmkQrK1NhwcWoPJF3FImaqHnG2PqPLWBt2GtSU]

RequestPolicy crushes Firefox when you scroll up and down a long menu of blocked destinations using the mouse wheel.
To reproduce the bug:

1. Setting strictness a full domain.
2. Open http://test-ipv6.com/ site.
3. Allow http://test-ipv6.com → http://ipv4.test-ipv6.com, http://test-ipv6.com → http://ipv6.test-ipv6.com, http://test-ipv6.com → http://ds.test-ipv6.com, http://test-ipv6.com → http://mtu1280.test-ipv6.com.
4. Move the mouse cursor over the list of blocked destinations.
5. Quickly roll the mouse wheel up and down several times.

[SCmkQrK1NhwcWoPJF3FImaqHnG2PqPLWBt2GtSU]

Fixed in Firefox.