Confidence in HTML5 has been shaken as Facebook abandons its app, raising doubt for business owners as to whether HTML5 is right for their site. If Zuckerberg doesn’t want it, why should we? HTML5 has been one of the biggest tech trends of the year, with the markup going from strength to strength, until now. Facebook’s Zuckerberg has said that building an app based on the standard was “one of the biggest mistakes, if not the biggest strategic mistake” that Facebook has ever made. The social giant saw ratings in the app store skyrocket from just one star to 4.5…