Remove WebBackForwardListItems when their owning page goes away

Remove WebBackForwardListItems when their owning page goes away
https://bugs.webkit.org/show_bug.cgi?id=134709
<rdar://problem/17584645>

Reviewed by Dan Bernstein.

* Shared/WebBackForwardListItem.cpp:
(WebKit::WebBackForwardListItem::create):
(WebKit::WebBackForwardListItem::WebBackForwardListItem):
* Shared/WebBackForwardListItem.h:
(WebKit::WebBackForwardListItem::pageID):
Add the associated PageID to the WebBackForwardListItem.

* UIProcess/WebBackForwardList.cpp:
(WebKit::WebBackForwardList::restoreFromState):
Push the current PageID onto the WebBackForwardListItem.

* UIProcess/WebProcessProxy.cpp:
(WebKit::WebProcessProxy::removeWebPage):
Remove all of the WebBackForwardListItems from m_backForwardListItemMap when
the page they are associated with is removed.

(WebKit::WebProcessProxy::addBackForwardItem):
Push the PageID from the WebProcess onto the WebBackForwardListItem.

* UIProcess/WebProcessProxy.h:
* UIProcess/WebProcessProxy.messages.in:
* WebProcess/WebPage/WebBackForwardListProxy.cpp:
(WebKit::idToHistoryItemMap):
(WebKit::historyItemToIDMap):
(WebKit::updateBackForwardItem):
(WebKit::WebBackForwardListProxy::addItemFromUIProcess):
(WebKit::WK2NotifyHistoryItemChanged):
(WebKit::WebBackForwardListProxy::idForItem):
(WebKit::WebBackForwardListProxy::addItem):
(WebKit::WebBackForwardListProxy::goToItem):
(WebKit::WebBackForwardListProxy::close):
* WebProcess/WebPage/WebBackForwardListProxy.h:
* WebProcess/WebPage/WebPage.cpp:
(WebKit::WebPage::restoreSession):
Keep track of the PageID that back-forward items were created by.
Pass the PageID along when registering WebBackForwardListItems.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@170902 268f45cc-cd09-0410-ab3c-d52691b4dbfc