Searching in media library while creating a gallery hides filtered images and resets the search box

[apeatling]

Running r22326 on Chrome 22.0.1229.94.

Issue:

Using the new media UI -- Using the search box, then creating a gallery and returning to the media library, images that were filtered are hidden and the search box is reset. There is no way to get the filtered images to show again.

To reproduce:

1. Select some images to add to a gallery.
2. Add some filter terms into the search box so at least some of the images are filtered out.
3. Hit the "Create a new gallery" button.
4. Hit the "Return to media library" button.
5. Images that were previously filtered are still hidden and the search box is reset.

[koopersmith]

In 22487:

Media: Ensure search box reflects actual search state.

• Also switches search box to use <input type="search" /> to take advantage of browser UI to clear the field.

fixes #22315, see #21390.