Fix api.DOMHighResTimestamp.mdn_url (#5260)
Fix api.DOMHighResTimestamp.mdn_url (#5260)

This is purely cosmetic change as the server uses case-insensitive paths.
chrisdavidmills/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data,mdn/browser-compat-data