Filed by: shindli [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer.html#?job_id=270467060&repo=mozilla-central
Full log: https://queue.taskcluster.net/v1/task/BOD4S1h-TdCAXcsm4-9eDQ/runs/0/artifacts/public/logs/live_backing.log

[task 2019-10-09T14:27:29.779Z] 14:27:29 INFO - TEST-OK | devtools/client/inspector/test/browser_inspector_highlighter-selector_01.js | took 1462ms
[task 2019-10-09T14:27:29.801Z] 14:27:29 INFO - checking window state
[task 2019-10-09T14:27:29.822Z] 14:27:29 INFO - TEST-START | devtools/client/inspector/test/browser_inspector_highlighter-selector_02.js
[task 2019-10-09T14:27:30.598Z] 14:27:30 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "CLEAR_FLEXBOX"
[task 2019-10-09T14:27:30.602Z] 14:27:30 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "UPDATE_GRIDS"
[task 2019-10-09T14:27:30.624Z] 14:27:30 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "UPDATE_OFFSET_PARENT"
[task 2019-10-09T14:27:30.631Z] 14:27:30 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "UPDATE_LAYOUT"
[task 2019-10-09T14:27:30.652Z] 14:27:30 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "CLEAR_FLEXBOX"
[task 2019-10-09T14:27:30.693Z] 14:27:30 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "UPDATE_OFFSET_PARENT"
[task 2019-10-09T14:27:30.694Z] 14:27:30 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "UPDATE_LAYOUT"
[task 2019-10-09T14:27:31.259Z] 14:27:31 INFO - GECKO(10552) | MEMORY STAT | vsize 7276MB | vsizeMaxContiguous 70119567MB | residentFast 433MB | heapAllocated 158MB
[task 2019-10-09T14:27:31.261Z] 14:27:31 INFO - TEST-OK | devtools/client/inspector/test/browser_inspector_highlighter-selector_02.js | took 1433ms
[task 2019-10-09T14:27:31.282Z] 14:27:31 INFO - checking window state
[task 2019-10-09T14:27:31.303Z] 14:27:31 INFO - TEST-START | devtools/client/inspector/test/browser_inspector_highlighter-xbl.js
[task 2019-10-09T14:27:32.019Z] 14:27:32 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "CLEAR_FLEXBOX"
[task 2019-10-09T14:27:32.021Z] 14:27:32 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "UPDATE_GRIDS"
[task 2019-10-09T14:27:32.033Z] 14:27:32 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "UPDATE_OFFSET_PARENT"
[task 2019-10-09T14:27:32.036Z] 14:27:32 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "UPDATE_LAYOUT"
[task 2019-10-09T14:27:32.205Z] 14:27:32 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "CLEAR_FLEXBOX"
[task 2019-10-09T14:27:32.207Z] 14:27:32 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "UPDATE_OFFSET_PARENT"
[task 2019-10-09T14:27:32.214Z] 14:27:32 INFO - GECKO(10552) | console.log: "[DISPATCH] action type:" "UPDATE_LAYOUT"
[task 2019-10-09T14:27:33.176Z] 14:27:33 INFO - TEST-INFO | started process screenshot
[task 2019-10-09T14:27:33.450Z] 14:27:33 INFO - TEST-INFO | screenshot: exit 0
[task 2019-10-09T14:27:33.454Z] 14:27:33 INFO - Buffered messages logged at 14:27:31
[task 2019-10-09T14:27:33.455Z] 14:27:33 INFO - Entering test bound
[task 2019-10-09T14:27:33.457Z] 14:27:33 INFO - Adding a new tab with URL: http://example.com/browser/devtools/client/inspector/test/doc_inspector_highlighter_xbl.xul
[task 2019-10-09T14:27:33.458Z] 14:27:33 INFO - Tab added and finished loading
[task 2019-10-09T14:27:33.460Z] 14:27:33 INFO - Opening the inspector
[task 2019-10-09T14:27:33.462Z] 14:27:33 INFO - Opening the toolbox
[task 2019-10-09T14:27:33.467Z] 14:27:33 INFO - Console message: [JavaScript Error: "Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”)." {file: "chrome://global/content/elements/panel.js" line: 62}]
[task 2019-10-09T14:27:33.470Z] 14:27:33 INFO - Console message: [JavaScript Error: "Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”)." {file: "chrome://global/content/elements/panel.js" line: 62}]
[task 2019-10-09T14:27:33.472Z] 14:27:33 INFO - Console message: [JavaScript Error: "Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”)." {file: "chrome://global/content/elements/panel.js" line: 62}]

This started permafailing on win arch64 as well as all artifact builds since Bug 1510785. Also see comments from :whimboo on Bug 1587662

This should be fixed by the artifact build fix in Bug 1587662.