1. srcdoc attribute for iframes

    Override the content specified in the `src` attribute (if present) with HTML content within the attribute.

  2. htmlframeelement api: src

  3. htmliframeelement api: src

  4. htmliframeelement api: srcdoc

  5. html element: frame: src

  6. html element: iframe: src

  7. html element: iframe: srcdoc

  8. headers http header: content-security-policy: fenced-frame-src

  9. headers http header: content-security-policy: frame-src