"The removeFormat command" section should include <del> as target of the command

[masayuki-nakano]

https://w3c.github.io/editing/execCommand.html#removeformat-candidate

A removeFormat candidate is an editable HTML element with local name "abbr", "acronym", "b", "bdi", "bdo", "big", "blink", "cite", "code", "dfn", "em", "font", "i", "ins", "kbd", "mark", "nobr", "q", "s", "samp", "small", "span", "strike", "strong", "sub", "sup", "tt", "u", or "var".

It includes <ins> but not include <del>. This really does not make sense without specific comment. I guess that it's just forgotten to be included into this list.

Unfortunately, Chrome conforms to current list, but they should be changed it.