by the way, using [].slice.call(document.querySelector("video").textTracks) does work (thanks for John from JWPlayer for checking)

Unable to reproduce the issue on the reported chrome version #70.0.3538.110 and latest stable #	71.0.3578.80 using Ubuntu 14.04 and Ubuntu 17.10 by following below steps.

Steps:
=====
1.Launched chrome.
2.Navigated to "https://video-dev.github.io/hls.js/latest/demo/?src=https%3A%2F%2Fplayertest.longtailvideo.com%2Fadaptive%2Fcaptions%2Fplaylist.m3u8&demoConfig=eyJlbmFibGVTdHJlYW1pbmciOnRydWUsImF1dG9SZWNvdmVyRXJyb3IiOnRydWUsImVuYWJsZVdvcmtlciI6dHJ1ZSwiZHVtcGZNUDQiOmZhbHNlLCJsZXZlbENhcHBpbmciOi0xLCJsaW1pdE1ldHJpY3MiOi0xLCJ3aWRldmluZUxpY2Vuc2VVcmwiOiIifQ==".
3.Opened Devtools->Console.
4.Entered to Object.values(document.querySelector("video").textTracks), it returned "[TextTrack]" value.

Attached screenshot for reference.
@reporter: Could you please review the attached screenshot and let us know if anything is being missed here. Requesting you to check the issue on latest stable #71.0.3578.80 by creating a new profile without any apps and extensions in it, reset all flags to default and let us know if the issue still persists. You can download the latest chrome from- "https://www.chromium.org/getting-involved/dev-channel".
Thanks.!

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	911765_M70.png 319 KB View Download

Thanks! I’m rechecking this.

Thank you for providing more feedback. Adding the requester to the cc list.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

As per comment#6, adding Needs-Feedback label. Awaiting the response from reporter.

Thanks!