Daniel, I think you pasted information for the wrong backout. You referenced bug 1556857 but this is bug 1551902. Could you please double-check? :)
Bug 1551902 Comment 10 Edit History
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Daniel, I think you pasted information for the wrong backout. You referenced bug 1556857 but this is bug 1551902. Could you please double-check? :) browser_trackingUI_cryptominers.js was mentioned to be failing in the backout commit, so I went ahead and made a patch to fix that. It would be useful to see the push in treeherder to see if any other test failed. I was surprised - I thought I did a try push for this, and I remember seeing no relevant failures, but apparently I didn't paste the link in the bug... hmph.