Well, wrong. Here’s how it looks empty. But because I was bookmarking a PDF, Safari couldn’t extract the title and used the URL as title instead. And the “Description” field below made me believe THAT would be the field with the title that shows in the bookmarks menu.
All this for what? Saving the space of the labels in a dialog with 3 controls, plus the action buttons, that will be presented on a device with a large screen? The trade off is just wrong. Always show the field labels. Never use placeholders as labels.