{ WebIDLParseError: Syntax error at line 21, since `interface AccessibleNode`:
 attribute sequence<DOMString> states;
                               ^ Attributes cannot accept sequence types
    at l.error (/opt/JS/WEBIDL2/webidl2.js/dist/webidl2.js:1:3920)
    at parse (/opt/JS/WEBIDL2/webidl2.js/dist/webidl2.js:1:13677)
    at Function.parse (/opt/JS/WEBIDL2/webidl2.js/dist/webidl2.js:1:19341)
    at Function.parse (/opt/JS/WEBIDL2/webidl2.js/dist/webidl2.js:1:21613)
    at o (/opt/JS/WEBIDL2/webidl2.js/dist/webidl2.js:1:25420)
    at i (/opt/JS/WEBIDL2/webidl2.js/dist/webidl2.js:1:25585)
    at /opt/JS/WEBIDL2/webidl2.js/dist/webidl2.js:1:25884
    at K (/opt/JS/WEBIDL2/webidl2.js/dist/webidl2.js:1:26014)
    at Module.Q (/opt/JS/WEBIDL2/webidl2.js/dist/webidl2.js:1:26168)
    at idl2s (repl:2:24)
  name: 'WebIDLParseError',
  bareMessage: 'Attributes cannot accept sequence types',
  context: 'Syntax error at line 21, since `interface AccessibleNode`:\n attribute sequence<DOMString> states;\n                               ^',
  line: 21,
  sourceName: undefined,
  input: 'states;\n\n  [Frozen,',
  tokens:
   [ { type: 'identifier',
       value: 'states',
       trivia: ' ',
       line: 21,
       index: 26 },
     { type: ';', value: ';', trivia: '', line: 21, index: 27 },
     { type: '[', value: '[', trivia: '\n\n  ', line: 23, index: 28 },
     { type: 'identifier',
       value: 'Frozen',
       trivia: '',
       line: 23,
       index: 29 },
     { type: ',', value: ',', trivia: '', line: 23, index: 30 } ] }

https://dxr.mozilla.org/mozilla-central/source/dom/webidl/AccessibleNode.webidl