Introduce |editing.dom.HTMLIterable|, for using for-of for |HTMLSeleciton.prototype.options|, and |editing.dom.ancestorsOrSelf(node)| for "selectAll" command.
Introduce |EditingContext.prototype.setEndingSelectionAsEmpty()| for "selectAll" command with SELECT element.
Fix optional parameter handling in |EdigintContext.prototype.execCommand()|.
Make |ImmutableSelection| to support empty seleciton.
This patch is a preparation of introducing "selectAll" which set empty selection for SELECT element.
[testing] Set focus to selection focus and skip "undo" testing if needed.
This patch is a preparation of introducing "selectAll" command.
Introduce "selectAll" command.
[testing] Don't list "compatible" and "compatible_html" test cases.