<attachment>'s save button click event should always be of type "save". The attachment element attribute could just be `save` (without value), similar to `checked`. <rdar://106108684>
Pull request: https://github.com/WebKit/WebKit/pull/10963
Committed 261206@main (36c736481d50): <https://commits.webkit.org/261206@main> Reviewed commits have been landed. Closing PR #10963 and removing active labels.