Selection across multiple nodes crashes the browser

Trying to select text across more than one Text Node crashes the browser consistently with the following backtrace:

thread 'main' panicked at web/core/src/dom/dom_objects/node.rs:64:22:
Parent node does not contain child
stack backtrace:
   0: rust_begin_unwind
             at /rustc/65ea825f4021eaf77f1b25139969712d65b435a4/library/std/src/panicking.rs:619:5
   1: core::panicking::panic_fmt
             at /rustc/65ea825f4021eaf77f1b25139969712d65b435a4/library/core/src/panicking.rs:72:14
   2: core::panicking::panic_display
             at /rustc/65ea825f4021eaf77f1b25139969712d65b435a4/library/core/src/panicking.rs:168:5
   3: core::panicking::panic_str
             at /rustc/65ea825f4021eaf77f1b25139969712d65b435a4/library/core/src/panicking.rs:152:5
   4: core::option::expect_failed
             at /rustc/65ea825f4021eaf77f1b25139969712d65b435a4/library/core/src/option.rs:1988:5
   5: core::dom::dom_objects::node::Node::find_subtree_containing
   6: core::dom::boundary_point::BoundaryPoint::position_relative_to
   7: core::selection::Selection::extend_to
   8: core::browsing_context::BrowsingContext::handle_event
   9: <stormlicht::browser_application::BrowserApplication as glazier::window::WinHandler>::pointer_move
  10: glazier::backend::x11::window::Window::handle_motion_notify
  11: glazier::backend::x11::application::AppInner::run_inner
  12: glazier::application::Application::run
  13: stormlicht::browser_application::BrowserApplication::run
  14: stormlicht::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Wuelle / Stormlicht

Selection across multiple nodes crashes the browser #6