Why not shim ResizeObserver?

[matthew-dean]

One thing to consider is shimming ResizeObserver like: https://github.com/maslianok/react-resize-detector to make this even more performant when available.

[matthew-dean]

This is probably a better base library to look at (dependency of react-resize-detector) - https://github.com/que-etc/resize-observer-polyfill

[joeybaker]

Great idea! I'd happily take a PR that does this!