UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36

Steps to reproduce the problem:
1. Navigate to beta.latimes.com
2. Open up the sources pane of the debug tools.
3. Ctrl-P to open osd_listener.js
4. Right click and choose "Add source map..."
5. In the source map dialog, add a URL. The URL may be a bogus URL or a working URL (either has the same problem). 
6. Click add - notice that there are no messages alerting that the URL was bogus nor that the source map was loaded successfully. In fact, there is no UI change at all. It appears as if the add button does nothing.

What is the expected behavior?
Something - at least an error.

What went wrong?
Nothing at all happened.

Did this work before? N/A 

Chrome version: 63.0.3239.132  Channel: stable
OS Version: 
Flash Version: