[Affected versions]: - 63.0b10(snap), 63.0b13(snap) [Affected platforms]: - ubuntu 16.04LTS [Steps to reproduce]: 1. launch Firefox - snap build; 2. Access the following link: http://dl3.webmfiles.org/big-buck-bunny_trailer.webm 3. Right Click on the video; 4. Click on the Inspect Element option; [Expected result]: - section bellow can be expanded: - <video autoplay="" controls=""></video> [Actual result]: - the mentioned section cannot be expanded; - its lacking the triangle icon to expand it; - when trying to edit the html no extra content was displayed; [Regression range]: - will check asap, if possible [Additional notes]: - attached screenshot with the issue; - current nightly build is not affected by this issue;

- updated platforms since I noticed the issue on win7 and macOS 10.13 as well; - updated summary since it's not snap-build speciffic; - encountered the issue on 52.08.1ESR, 61.0b8, 63.0b12 normal builds.

This works fine for me on OSX using Nightly v64... can you test using that version or is this only an issue with snap builds?

Encountered the issue on 64.0a1(2018-09-10) on Ubuntu18, after updating to the current version the issue is fixed. Checked with the latest nightly on Win10 and macOS 10.10.5 and the issue does not reproduce on them either. I think we can mark this bug as resolved worksforme at this stage, I doubt that something will change for 63 keeping in mind the RC is out.