Tests Application Panel's handling of storages in iframes.

Initial tree...

Storage
 Local storage
  http://127.0.0.1:8000
  http://devtools.oopif.test:8000
 Session storage
  http://127.0.0.1:8000
  http://devtools.oopif.test:8000
 Extension storage
 IndexedDB
  Database-iframe
   Database-iframe
  Database-main-frame
 Cookies
  http://127.0.0.1:8000
  http://devtools.oopif.test:8000
 Private state tokens
 Shared storage
  http://127.0.0.1:8000
  http://devtools.oopif.test:8000
 Cache storage
 Storage buckets
Frames
 top
  indexeddb-in-iframe.html
   indexeddb-in-iframe.html
  inspected-page.html

Remove iframe from page...

Storage
 Local storage
  http://127.0.0.1:8000
 Session storage
  http://127.0.0.1:8000
 Extension storage
 IndexedDB
  Database-main-frame
 Cookies
  http://127.0.0.1:8000
  http://devtools.oopif.test:8000
 Private state tokens
 Shared storage
  http://127.0.0.1:8000
 Cache storage
 Storage buckets
Frames
 top
  inspected-page.html

Add iframe to page again...

Storage
 Local storage
  http://127.0.0.1:8000
  http://devtools.oopif.test:8000
 Session storage
  http://127.0.0.1:8000
  http://devtools.oopif.test:8000
 Extension storage
 IndexedDB
  Database-main-frame
  Database-iframe
   Database-iframe
 Cookies
  http://127.0.0.1:8000
  http://devtools.oopif.test:8000
 Private state tokens
 Shared storage
  http://127.0.0.1:8000
  http://devtools.oopif.test:8000
 Cache storage
 Storage buckets
Frames
 top
  indexeddb-in-iframe.html
   indexeddb-in-iframe.html
  inspected-page.html