Page previews should have titles
https://bugs.webkit.org/show_bug.cgi?id=139020

Reviewed by Tim Horton.

* UIProcess/API/Cocoa/WKViewPrivate.h:
Declare -_titleForPreviewOfURL:.

* UIProcess/API/mac/WKView.mm:
(-[WKView _titleForPreviewOfURL:]):
Stub implementation.

* UIProcess/mac/WKActionMenuController.mm:
(+[WKPagePreviewViewController previewPadding]):
Account for the title height.
(-[WKPagePreviewViewController loadView]):
Set correct autoresize masks on some views; create and configure a title view that is
horizontally and vertically centered.
(-[WKActionMenuController pagePreviewViewController:titleForPreviewOfURL:]):
WKPagePreviewViewControllerDelegate method; wrap -[WKView _titleForPreviewOfURL:].

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@176511 268f45cc-cd09-0410-ab3c-d52691b4dbfc