Call reloadStylesheets instead of reloadStylesheet in spec
Don’t use syntax themes in spec because they are inserted in shadow DOM
Don’t recycle the same composite disposable for stylesheet activation
Protect against stylesheets changing while detached
Go back to the plain “theme” group for theme stylesheets
Don’t rely on :focus selector for toHaveFocus matcher

:focus doesn’t work properly when focus is inside the shadow DOM of
an element, but document.activeElement does.
Account for shadow DOM when asserting on focus
Sample font styling when font config values change

We previously could do it whenever stylesheets changed, but these values
end up getting assigned to the global stylesheet for cascading reasons
and we’re only watching the local stylesheet. We poll the host elements
DOM properties, but forcing a sync poll when the config values change
makes behavior synchronous for specs and more responsive when changing
these values.
Proxy TextEditorView::find calls to the root inside the shadow DOM