Convert WebPreferences and VisitedLinkProvider to be bridged API::Objects

Convert WebPreferences and VisitedLinkProvider to be bridged API::Objects
https://bugs.webkit.org/show_bug.cgi?id=141002

Patch by Sam Weinig <sam@webkit.org> on 2015-01-28
Reviewed by Tim Horton.

* Shared/API/APIObject.h:
Add VisitedLinkProvider type.

* Shared/Cocoa/APIObject.mm:
(API::Object::newObject):
Allocate WebPreferences and VisitedLinkProvider as their Objective-C counterpart.

* UIProcess/API/Cocoa/WKPreferences.mm:
(-[WKPreferences init]):
Switch to constructInWrapper.

(-[WKPreferences dealloc]):
Call the WebPreferences destructor.

(-[WKPreferences _apiObject]):
Add implementation of the WKObject protocol.

* UIProcess/API/Cocoa/WKPreferencesInternal.h:
Convert to using ObjectStorage.

* UIProcess/API/Cocoa/_WKVisitedLinkProvider.mm:
(-[_WKVisitedLinkProvider init]):
Switch to constructInWrapper.

(-[_WKVisitedLinkProvider dealloc]):
Call the VisitedLinkProvider destructor.

(-[_WKVisitedLinkProvider _apiObject]):
Add implementation of the WKObject protocol.

* UIProcess/API/Cocoa/_WKVisitedLinkProviderInternal.h:
Convert to using ObjectStorage.

* UIProcess/VisitedLinkProvider.cpp:
(WebKit::VisitedLinkProvider::create):
* UIProcess/VisitedLinkProvider.h:
Switch create() to return a Ref.

* UIProcess/WebPreferences.h:
Make the constructor public for use by constructInWrapper.

* UIProcess/WebProcessPool.cpp:
(WebKit::WebProcessPool::createWebPage):
* UIProcess/WebProcessPool.h:
Store the VisitedLinkProvider in a Ref.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@179281 268f45cc-cd09-0410-ab3c-d52691b4dbfc