Fix for bugzilla bug 4573, make sure click() fires CLICK and not KHTML_CLICK,

	Fix for bugzilla bug 4573, make sure click() fires CLICK and not KHTML_CLICK,
	so that the click() method on checkboxes actually works.

	Also eliminate the WinIE compatibiilty for event.button and match the
	standard DOM behavior instead (like Firefox does).

        Reviewed by darin

        Test cases added: None, since one of the level 2 DOM tests changes to
	pass and tests this feature.

        * khtml/ecma/kjs_events.cpp:
        (KJS::DOMMouseEvent::getValueProperty):
        * khtml/html/html_elementimpl.cpp:
        (HTMLElementImpl::click):
        * layout-tests/dom/html/level2/html/HTMLInputElement21-expected.txt:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@10398 268f45cc-cd09-0410-ab3c-d52691b4dbfc