This PR fixes an extremely performance-crushing bug that was happening
in Safari and Chrome when iframes were present.
### Change Type
- [x] `patch` — Bug fix
### Test Plan
1. Create one hundred shapes
2. Create a gist or maps embed
3. Select all
If the app crashes or the rendering layers list grows to lots and lots
of layers, that's the bug.
### Release Notes
- [fix] iframe rendering issue
227c97a057