Illegal constructor exception in /bluetooth/characteristic/getDescriptors/gen-characteristic-is-removed.https.html

[georgeroman]

▶ Unexpected subtest result in /bluetooth/characteristic/getDescriptors/gen-characteristic-is-removed.https.html:
  │ FAIL [expected PASS] gen-characteristic-is-removed
  │   → Illegal constructor.
  │ 
  └ @https://web-platform.test:8443/bluetooth/resources/bluetooth-helpers.js:177:10

[jdm]

<script>new DOMException('a', 'b')</script>

This runs fine in Firefox and yields the following exception in Servo:

[2019-03-19T17:30:03Z ERROR script::dom::bindings::error] Error at file:///tmp/foo2.html:1:1 Illegal constructor.

[jdm]

I think we need to add Constructor(optional DOMString message = "", optional DOMString name) to DOMException.webidl like in Firefox: https://searchfox.org/mozilla-central/source/dom/webidl/DOMException.webidl#70

[jdm]

Oops, this is a duplicate of #22412.