Problem: Crash when removing a <mask>, <clipPath>, or <pattern> element
that’s referenced via url(#id), and then GC’ing it.
Cause: <mask>, <clipPath>, and <pattern> are laid out as resource boxes
attached to the referencing element's layout subtree, rather than their
own. So those survive cleanup of their DOM ancestor. Once a removed
<mask>/<clipPath>/<pattern> is collected, its resource box’s weak DOM
node pointer is null. And dereferencing that trips an assert — both
while painting and while tearing down the layout tree.
Fix: When a <mask>, <clipPath>, or <pattern> is removed, request a full
layout-tree update while the element’s still alive. That drops the stale
resource boxes (whose url(#id) references no longer resolve) before the
node gets collected.
Fixes https://github.com/LadybirdBrowser/ladybird/issues/10127
4bbc5e0950