function HTMLFile (socket) {
    io.Transport.XHR.apply(this, arguments);
  }
The HTMLFile transport creates a `forever iframe` based transport
for Internet Explorer. Regular forever iframe implementations will 
continuously trigger the browsers buzy indicators. If the forever iframe
is created inside a `htmlfile` these indicators will not be trigged.

@constructor
@extends {io.Transport.XHR}
@api public