Add spec URLs for newly-added CSS @property descriptors (#9378)
Add spec URLs for newly-added CSS @property descriptors (#9378)

This change adds spec URLs for the CSS @property "inherits",
"initial-value", and "syntax" descriptors.
chrisdavidmills/browser-compat-data,mdn/browser-compat-data,mdn/browser-compat-data,chrisdavidmills/browser-compat-data