Stop keeping a frame tree in the UIProcess
https://bugs.webkit.org/show_bug.cgi?id=81728

Reviewed by Oliver Hunt.

This patch removes the parent/child relationships of WebFrameProxys
in the UIProcess

* UIProcess/API/C/WKFrame.cpp:
(WKFrameCopyChildFrames):
(WKFrameGetParentFrame):
* UIProcess/API/C/WKFrame.h:
Null out the implementations of WKFrameCopyChildFrames and WKFrameGetParentFrame,
but keep them around as their symbols are still needed for nightlies.

* UIProcess/WebFrameProxy.cpp:
(WebKit::WebFrameProxy::WebFrameProxy):
(WebKit::WebFrameProxy::disconnect):
* UIProcess/WebFrameProxy.h:
Remove parent/child connections.

* UIProcess/WebPageProxy.cpp:
(WebKit::WebPageProxy::didCreateSubframe):
(WebKit::WebPageProxy::didRemoveFrameFromHierarchy):
* UIProcess/WebPageProxy.h:
* UIProcess/WebPageProxy.messages.in:
* WebProcess/WebCoreSupport/WebFrameLoaderClient.cpp:
(WebKit::WebFrameLoaderClient::didSaveToPageCache):
(WebKit::WebFrameLoaderClient::didRestoreFromPageCache):
* WebProcess/WebPage/WebFrame.cpp:
(WebKit::WebFrame::createSubframe):
Remove/Update messages that only served to update the parent/child connection.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141708 268f45cc-cd09-0410-ab3c-d52691b4dbfc