Browsers implementing CORB blocks access to webirc gateways

[kenneaal]

Browsers have with recent updates begun to default to enabling CORB. This can cause problems with webirc gateways, as the server does not send Origin headers. This makes the Kiwi client silently fail after clicking Connect; the error is only evident in the console.

A possible solution is to enable such headers to be added in the config file, or tied to the domain whitelist already there.

Example block message from console:
Failed to load https://example.com:4443/webirc/kiwi/info?t=1538813226441: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'https://other.example.com' is therefore not allowed access.
abstract-xhr.js:132 Cross-Origin Read Blocking (CORB) blocked cross-origin response https://example.com:4443/webirc/kiwi/info?t=1538813226441 with MIME type text/plain. See https://www.chromestatus.com/feature/5629709824032768 for more details.
r._start @ abstract-xhr.js:132
(anonymous) @ abstract-xhr.js:21
setTimeout (async)
r @ abstract-xhr.js:20
r @ xhr-cors.js:8
r @ info-ajax.js:19
r._getReceiver @ info-receiver.js:39
r.doXhr @ info-receiver.js:56
(anonymous) @ info-receiver.js:25
setTimeout (async)
r @ info-receiver.js:24
r @ main.js:121
n.reconnect.n.connect @ ServerConnection.js:60
r.connect @ ServerConnection.js:182
value @ browser.js:8
value @ browser.js:8
s.connect @ IrcClient.js:100
startUp @ Welcome.vue?4f7d:180
n @ vue.common.js:193
formSubmit @ Welcome.vue?4f7d:122
n @ vue.common.js:192
submit @ Welcome.vue?7742:1
e @ vue.common.js:2006
t._withTask.t._withTask @ vue.common.js:1804