RES is broken in Chrome Beta/Dev and Canary builds

What's up?

RES is broken in tonight's update of Chrome Dev (Version 64.0.3251.0 (Official Build) dev (64-bit)), and in the canary build (Version 64.0.3252.0 (Official Build) canary (64-bit) )

Symptoms:

1. Resources in the extension fails to load - such as the icon for the cogwheel, and pretty much all of RES' stylesheet
2. The RES settings console does not show up when you try to open it via the now-missing RES cogwheel.
3. It's possible to coerce the cogwheel to show up by toggling "Show this subreddit's theme", but it's impossible to close it without reloading the page.

Where does it happen?

On every page where RES is enabled.

Screenshots or mock-ups

Screenshot of symptom: https://imgur.com/jDEDuv4

What browser extensions are installed?

RES only (5.8.6)

• Night mode: false
• RES Version: 5.8.6
• Browser: Chrome
• Browser Version: 64
• Cookies Enabled: true
• Reddit beta: false