Update artwork for some action menu items

Update artwork for some action menu items
https://bugs.webkit.org/show_bug.cgi?id=138634
<rdar://problem/18871984>

Reviewed by Anders Carlsson.

* Resources/OpenInNewWindowTemplate.pdf: Removed.
* UIProcess/mac/WKActionMenuController.mm:
(-[WKActionMenuController _createActionMenuItemForTag:]):
(webKitBundleImageNamed): Deleted.
* WebKit2.xcodeproj/project.pbxproj:
Get rid of our custom art, and use system art for two more items.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@175983 268f45cc-cd09-0410-ab3c-d52691b4dbfc