Reviewed by John.

    Reviewed by John.

	<rdar://problem/3487195>: Implement responseXML property for XMLHttpRequest

        * khtml/ecma/xmlhttprequest.cpp:
        (KJS::XMLHttpRequest::getValueProperty): Implemented responseXML by parsing the
	document and returning it.
        (KJS::XMLHttpRequest::XMLHttpRequest): Initialize new field
        * khtml/ecma/xmlhttprequest.h:

        * khtml/ecma/kjs_window.cpp:
	(Windw::get): Forgot this in last commit; add XMLSerializer
	constructor.
        * khtml/ecma/kjs_window.lut.h:
	* khtml/ecma/Makefile.am: Forgot to include this in the last commit.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@5741 268f45cc-cd09-0410-ab3c-d52691b4dbfc