Add partial_implementation to Element members moved from HTMLElement (#13117)
Add partial_implementation to Element members moved from HTMLElement (#13117)

This was already done in some places. Do it consistently in
Element.json, following this guideline:
https://github.com/mdn/browser-compat-data/blob/main/docs/data-guidelines.md#apis-moved-on-the-prototype-chain
mdn/browser-compat-data,mdn/browser-compat-data,chrisdavidmills/browser-compat-data,chrisdavidmills/browser-compat-data