13         lastEventId: '', source: null, ports: []  property
20         lastEventId: '', source: null, ports: []  property
27         lastEventId: '0', source: null, ports: []  property
34         lastEventId: 'foo', source: null, ports: []  property
38       ['messageerror', { lastEventId: 'foo', source: dummyPort }],  property
41         lastEventId: 'foo', source: dummyPort, ports: []  property
45       ['message', { ports: [dummyPort], source: null }],  property
48         lastEventId: '', source: null, ports: [dummyPort]  property
55       type, data, origin, lastEventId, source, ports  property
62     new MessageEvent('message', { source: 1 });  property
68     new MessageEvent('message', { source: {} });  property