Browsers supported by EUI has changed in the last year, most notably the removal of IE11 from the list. As such, several components have residual code to support one or more browsers that no longer require support and could be improved or simplified. This includes areas such as web APIs, browser eventing, CSS features, etc.

Use this issue to track potential refactors.

• EuiResizeObserver. The ResizeObserver API is now supported by all supported browsers. The makeCompatibleObserver fallback method is no longer necessary.