unload handler

        * khtml/khtml_part.cpp: (KHTMLPart::begin): Call updatePolicyBaseURL to set
	the "policy base URL" on the documents so the cookie can be based on the URL
	of the main document.

        * khtml/dom/html_document.h: Add setPolicyBaseURL.
        * khtml/dom/html_document.cpp: (HTMLDocument::setPolicyBaseURL): Call the impl.

        * khtml/html/html_documentimpl.h: Add policyBaseURL, setPolicyBaseURL.
        * khtml/html/html_documentimpl.cpp: (HTMLDocumentImpl::setCookie): Pass the
	base URL that's stored here instead of getting at the part through the view,
	since the view will be 0 during the unload event.

        * kwq/KWQKHTMLPartImpl.h: Add updatePolicyBaseURL and setPolicyBaseURL.
        * kwq/KWQKHTMLPartImpl.mm:
        (KWQKHTMLPartImpl::updatePolicyBaseURL): Set the base URL based on the URL
	if this is the topmost part, based on the parent's policy base URL if this
	is not the topmost part.
        (KWQKHTMLPartImpl::setPolicyBaseURL): Change the policy base URL for this
	part and all the subparts.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@2180 268f45cc-cd09-0410-ab3c-d52691b4dbfc