css.types.angle-percentage: delete child elements (#5258)
css.types.angle-percentage: delete child elements (#5258)

* Fix mdn_url for css.types.angle-percentage

* Delete redundant information

chrisdavidmills/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data,mdn/browser-compat-data