Bug 1564737 [wpt PR 17639] - Update interfaces/WebIDL.idl, a=testonly

Automatic update from web-platform-tests
Update interfaces/WebIDL.idl (#17639)

Source: https://github.com/tidoust/reffy-reports/blob/33bc5b1/whatwg/idl/WebIDL.idl
Build: https://travis-ci.org/tidoust/reffy-reports/builds/554091846
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wpt-commits: 8b34e2aa8b5f22da94bc2c649f6bbdbba65cf40e
wpt-pr: 17639

testing/web-platform/tests/interfaces/WebIDL.idl

@@ -10,7 +10,8 @@ typedef (Int8Array or Int16Array or Int32Array or
 typedef (ArrayBufferView or ArrayBuffer) BufferSource;
 [
  Exposed=(Window,Worker),
- Constructor(optional DOMString message = "", optional DOMString name = "Error")
+ Constructor(optional DOMString message = "", optional DOMString name = "Error"),
+ Serializable
 ]
 interface DOMException { // but see below note about ECMAScript binding
   readonly attribute DOMString name;