Bug 1390027 didn't add tests so it was regressed by bug 1457517. Please fix again and add tests. 1. Open web console 2. Enter this code: var obj = Object.create(null); obj.__proto__ = []; obj; Result: Object { undefined: undefined, undefined: undefined, undefined: undefined } Expected: Object { __proto__: [] } 3. Inspect the object Result: no property Expected: ▶ __proto__ : Array []

I can reproduce this bug, thanks for the report Oriol! Honza

This patch only remove the extends calls that were used to transpile object spread syntax. A test is added to ensure we don't regress this in the future.

Pushed by nchevobbe@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/2519c4f594cb Fix __proto__ handling in ObjectInspector; r=Oriol.

Please request Beta approval on this when you get a chance.

Comment on attachment 9030638 [details] Bug 1496044 - Fix __proto__ handling in ObjectInspector; r=Oriol. [Beta/Release Uplift Approval Request] Feature/Bug causing the regression: None User impact if declined: In some cases, printed object in the console would show erroneous information Is this code covered by automated tests?: Yes Has the fix been verified in Nightly?: Yes Needs manual test from QE?: Yes If yes, steps to reproduce: **Steps to reproduce** 1. Open the console 2. Evaluate the following code: ``` var obj = Object.create(null); obj.__proto__ = [];obj; ``` **Expected results** You get the following result: Object { __proto__: [] } --- List of other uplifts needed: None Risk to taking this patch: Low Why is the change risky/not risky? (and alternatives if risky): DevTools only, tested, only changes how we create the reps bundle (no lcode logic change) String changes made/needed:

Comment on attachment 9030638 [details] Bug 1496044 - Fix __proto__ handling in ObjectInspector; r=Oriol. [Triage Comment] Fix for erroneous information being printed in the console. Approved for 65.0b6.

I successfully reproduced the issue on Firefox Nightly 64.0a1 (2018-10-03) under Ubuntu 18.04 (x64) using the STR from Comment 0. The issue is no longer reproducible on Firefox Beta 65.0b6 and Firefox Nightly 66.0a1 (2018-12-21). Tests were performed under Windows 10 (x64), Ubuntu 18.04 (x64) and macOS 10.12.