Reviewed by Ken and John.

    Reviewed by Ken and John.

	Re-fixed a specific case of the following:

	<rdar://problem/3790449> REGRESSION (Mail): underline behavior is flaky because of how CSS handles text-decoration

	Oddly, Cmd-B, Cmd-U, type some text, return, Cmd-U, Cmd-B, type
	some text, worked fine. But hitting the second Cmd-B before the
	second Cmd-U still failed to remove underlining. The reason for
	this is that our code to compute the style of the current position
	did not work when you had a typing style and were positioned right
	at a <br> element. For various reasons, this did not show up for
	bold and italic, since those are handled through the font manager.

	The following change fixes this - for elements that can't have
	children, we add the dummy span after the element of interest,
	rather than as a child of it.

        * khtml/khtml_part.cpp:
        (KHTMLPart::selectionComputedStyle):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@8588 268f45cc-cd09-0410-ab3c-d52691b4dbfc