https://bugs.webkit.org/show_bug.cgi?id=125316
<rdar://problem/15560614>

Reviewed by Dan Bernstein.

Use WeakObjCPtr for the delegates.

* UIProcess/API/Cocoa/WKBrowsingContextController.h:
* UIProcess/API/Cocoa/WKBrowsingContextController.mm:
(didStartProvisionalLoadForFrame):
(didReceiveServerRedirectForProvisionalLoadForFrame):
(didFailProvisionalLoadWithErrorForFrame):
(didCommitLoadForFrame):
(didFinishLoadForFrame):
(didFailLoadWithErrorForFrame):
(didStartProgress):
(didChangeProgress):
(didFinishProgress):
(didChangeBackForwardList):
(setUpPagePolicyClient):
(-[WKBrowsingContextController loadDelegate]):
(-[WKBrowsingContextController setLoadDelegate:]):
(-[WKBrowsingContextController policyDelegate]):
(-[WKBrowsingContextController setPolicyDelegate:]):
(-[WKBrowsingContextController historyDelegate]):
(-[WKBrowsingContextController setHistoryDelegate:]):
* UIProcess/API/Cocoa/WKBrowsingContextControllerInternal.h:
* UIProcess/API/Cocoa/WKConnection.mm:
(didReceiveMessage):
(didClose):
(-[WKConnection delegate]):
(-[WKConnection setDelegate:]):
* UIProcess/API/Cocoa/WKProcessGroup.mm:
(didCreateConnection):
(getInjectedBundleInitializationUserData):
(didNavigateWithNavigationData):
(didPerformClientRedirect):
(didPerformServerRedirect):
(didUpdateHistoryTitle):
(-[WKProcessGroup delegate]):
(-[WKProcessGroup setDelegate:]):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@160191 268f45cc-cd09-0410-ab3c-d52691b4dbfc