[1] Define get(All)ResponseHeader(s) in terms of Fetch ( (annevk著, 6/7/2016, 2:16:42 PM)) https://github.com/whatwg/xhr/commit/ecce3904ace0dbe382a652ea1d8e29c7885fe8c4
[2] Stop using "combined value" (annevk著, 11/27/2018, 2:18:25 PM) https://github.com/whatwg/xhr/commit/0d4253c784d2b71ca5bf6648c67f95b82bb8b239
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