spec: https://github.com/tc39/proposal-explicit-resource-management It has been promoted to stage 3. https://github.com/tc39/proposals/commit/b0e427418d081a5b5014f0bf18fc414a16ffa928
- SpiderMonkey https://bugzilla.mozilla.org/show_bug.cgi?id=1569081 - V8 https://bugs.chromium.org/p/v8/issues/detail?id=13559
<rdar://problem/103209363>