[whatwg] Add more types of DOM as part of Form

[jingwei lv]

Recently I am working with some web frameworks with mongodb(non relational
database). There is one type of field called dict, similar with BSON, or
JSON. In general, when defining a table in db in modern frameworks, it also
can be generated a form in html, which is intuitive and convenient. Well,
but those types such as list, dict in db are not supported in the
generation of a form in those frameworks. For example, if you have a field
typed list, you need a html DOM something like a list of <input
type="text"/>, and the length can be changed dynamically. Of course, you
can do define those things by hand. But since the non relational db will be
used more, also in Semantic web. It will be much simple for web designer or
programmer. The same for dictionary type.