[infra-tests] Stability checker: escape vertical bar to avoid splitting table cells (#5539)

See https://github.com/w3c/web-platform-tests/pull/5528#issuecomment-293015848
`[[GetOwnProperty]] - Properties on cross-origin objects should be reported |own|`

View on GitHub: https://github.com/w3c/web-platform-tests/pull/5539

Received on Wednesday, 12 April 2017 14:04:05 UTC