MISTMATCHED_CLOSE_TAG improvements.

[flukeout]

One of the ways this message shows up is...

In this case, the problem is really that there isn't an OPENING version of this tag anywhere, so it's a stray. It really shouldn't be trying to indicate that the body should be closed. I wonder how we can account for this.

• If the unclosed tag is a body tag. We shouldn't report the error in this way.