Remove api.Element.[overflow/underflow]_event from BCD (#12975)
Remove api.Element.[overflow/underflow]_event from BCD (#12975)

This PR removes the irrelevant `overflow_event` and `underflow_event` members of the `Element` API as per the corresponding [data guidelines](https://github.com/mdn/browser-compat-data/blob/main/docs/data-guidelines.md#removal-of-irrelevant-features). The lack of current support has been confirmed by manual testing using the example on the MDN page, even if the current BCD suggests support.
mdn/browser-compat-data,chrisdavidmills/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data