Request for Mozilla Position on an Emerging Web Specification

• Specification Title: Navigation API
• Specification or proposal URL: https://github.com/wicg/navigation-api / incomplete spec at https://wicg.github.io/navigation-api/ (HTML PR: Add the navigation API whatwg/html#8502)
• Mozillians who can provide input (optional): @annevk and @smaug---- have been very helpful discussing this so far