{"action":"opened","issue":{"url":"https://api.github.com/repos/tc39/ecma262/issues/233","labels_url":"https://api.github.com/repos/tc39/ecma262/issues/233/labels{/name}","comments_url":"https://api.github.com/repos/tc39/ecma262/issues/233/comments","events_url":"https://api.github.com/repos/tc39/ecma262/issues/233/events","html_url":"https://github.com/tc39/ecma262/issues/233","id":120859524,"number":233,"title":"isConcatSpreadable set to true","user":{"login":"nzakas","id":38546,"avatar_url":"https://avatars.githubusercontent.com/u/38546?v=3","gravatar_id":"","url":"https://api.github.com/users/nzakas","html_url":"https://github.com/nzakas","followers_url":"https://api.github.com/users/nzakas/followers","following_url":"https://api.github.com/users/nzakas/following{/other_user}","gists_url":"https://api.github.com/users/nzakas/gists{/gist_id}","starred_url":"https://api.github.com/users/nzakas/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/nzakas/subscriptions","organizations_url":"https://api.github.com/users/nzakas/orgs","repos_url":"https://api.github.com/users/nzakas/repos","events_url":"https://api.github.com/users/nzakas/events{/privacy}","received_events_url":"https://api.github.com/users/nzakas/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-12-07T20:23:56Z","updated_at":"2015-12-07T20:23:56Z","closed_at":null,"body":"I may be missing it, but I can't seem to find anything in the spec indicating that `@@isConcatSpreadable` should be `true` for arrays.\r\n\r\nFor `@@hasInstance`, I noted this entry explaining the default value for functions: http://tc39.github.io/ecma262/#sec-function.prototype-@@hasinstance\r\n\r\nI was expected to see something similar for `Array.prototype`. Is this defined somewhere?"}}