Now that we want to support multi-view, we need to either: 1. Remove the workaround to safely remove slot elements in Safari, or 2. Fix it to support multi-view (can't use `flutterViewEmbedder.glassPaneShadow` anymore). According to [this comment](https://github.com/flutter/flutter/issues/85816#issuecomment-1122638147), this is the right time to remove the workaround ð I tested on Desktop Safari and iOS Safari and wasn't able to reproduce the crash reported in https://github.com/flutter/flutter/issues/84832. Fixes https://github.com/flutter/flutter/issues/85816 Part of https://github.com/flutter/flutter/issues/134443