Pass encoded back/forward tree data from the WebProcess to the UIProcess

Reviewed by Darin Adler.

Remove the WKBackForwardListItemCopyOriginalURL API as it's not needed:
* UIProcess/API/C/WKBackForwardListItem.cpp:
* UIProcess/API/C/WKBackForwardListItem.h:
* UIProcess/API/qt/qwkhistory.cpp:
* UIProcess/API/qt/qwkhistory.h:
        
* UIProcess/WebBackForwardListItem.cpp:
(WebKit::WebBackForwardListItem::WebBackForwardListItem):
* UIProcess/WebBackForwardListItem.h:
(WebKit::WebBackForwardListItem::create):
(WebKit::WebBackForwardListItem::setBackForwardData):
(WebKit::WebBackForwardListItem::backForwardData):
        
* UIProcess/WebProcessProxy.cpp:
(WebKit::WebProcessProxy::addBackForwardItem):
* UIProcess/WebProcessProxy.h:
        
* UIProcess/WebProcessProxy.messages.in:
        
* WebProcess/WebPage/WebBackForwardListProxy.cpp:
(WebKit::updateBackForwardItem):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@74970 268f45cc-cd09-0410-ab3c-d52691b4dbfc