Intent to Ship - sandbox-"allow-downloads"

[Sebastian Streich]

Intent to Ship - sandbox-"allow-downloads"
Summary:
Firefox 82 will start to block downloads that are initiated by sandboxed
iframes unless the embedder has opted in via setting the “allow-download”
sandbox-flag.

Bug:

Bugzilla 1558394 <https://bugzilla.mozilla.org/show_bug.cgi?id=1558394>

Standards:

- whatwg/attr-iframe-sandbox-allow-downloads
<https://html.spec.whatwg.org/multipage/origin.html#attr-iframe-sandbox-allow-downloads>
<https://html.spec.whatwg.org/multipage/links.html#allowed-to-download>
- whatwg/#allowed-to-download
<https://html.spec.whatwg.org/multipage/links.html#allowed-to-download>

Platform coverage:

all platforms

Estimated or target release:

Firefox 82

Preference:

This feature is controlled via:

dom.block_download_in_sandboxed_iframes

web-platform-tests:

This feature is covered by wpt tests.

Other browsers:

Safari: no support

Chrome <https://www.chromestatus.com/feature/5706745674465280>: Shipped
with Chrome 83


Secure contexts:

This feature isn’t restricted to Secure Contexts.