1. srcdoc attribute for iframes

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

  2. element api: setattribute: requires `value` parameter to be `trustedhtml` instance (for `iframe.srcdoc`), or `trustedscripturl` (for html `script.src`, and svg `script.href`) when trusted types are enforced

  3. htmlframeelement api: src

  4. htmliframeelement api: src

  5. htmliframeelement api: srcdoc

  6. htmliframeelement api: srcdoc: requires `trustedhtml` instance when trusted types are enforced

  7. html element: frame: src

  8. html element: iframe: src

  9. html element: iframe: srcdoc

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

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