HTMLForm: Use ObjectFactory instead of Reflection

HTMLForm: Use ObjectFactory instead of Reflection

ObjectFactory has a hack that constructs an object directly if there are
less than 10 parameters, which there typically is for HTMLForm classes.
This is faster than using ReflectionClass, and whenever ObjectFactory is
updated to take advantage of the splat operator, this will automatically
use it as well.

And use ::class while we're at it.

Change-Id: I7a696c127c237713448b165b9b4faee13f4ff88e