* History.subproj/WebHistoryItem.m:
        (-[WebHistoryItem _retainIconInDatabase:]): Get the URL with [self URL].
        (-[WebHistoryItem initWithURL:target:parent:title:]): Set up _URLString.
        (-[WebHistoryItem dealloc]): Release _URLString.
        (-[WebHistoryItem URL]): Make a URL from _URLString.
        (-[WebHistoryItem icon]): Use [self URL] instead of _URL.
        (-[WebHistoryItem setURL:]): Store a URL string.
        (-[WebHistoryItem hash]): Use the URL string's hash.
        (-[WebHistoryItem isEqual:]): Compare the URL strings.
        (-[WebHistoryItem description]): Use _URLString.
        (-[WebHistoryItem dictionaryRepresentation]): Use _URLString.
        (-[WebHistoryItem initFromDictionaryRepresentation:]): Call through to
	the other init functions so we have only one designated initializer.
	Leave the date as nil if there's no date in the dictionary instead of
	setting the date to 0.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@2598 268f45cc-cd09-0410-ab3c-d52691b4dbfc