Implement IHtmlString

[brianbaker]

Implementing IHtmlString would make it easier to incorporate Elements or other components based on Elements into Razor views. I think if Node implemented IHtmlString then that would allow Element, Fragment, Node, and Text to be rendered in a Razor view without needing to call ToString() and MvcHtmlString.Create(). Any thoughts/concerns?

[AndersRaz]

That seems like a good idea. It think it's similar to IRenderable. I can't think of any drawbacks.