[editing] Make |EditingContext.prototype.splitNode| and |EditingContext.prototype.splitNodeLeft| to copy "name" attribute of "A" element for Chrome compatibility.
nodes: Revise start node splitting in |editing.nodes.setUpEffectiveNodes()|.
This patch is a preparation of fixing "createLink" command.
createLink: Utilize "editing.nodes.setUpEffectiveNodes()| into "createLink" command.