URL: https://accounts.google.com/signin/v2/challenge/

Browser / Version: Firefox 59.0
Operating System: Mac OS X 10.13
Tested Another Browser: Yes

Problem type: Site is not usable
Description: "Something went wrong" popup on Google security key login screen (before even inserting key)
Steps to Reproduce:

1. Load security key login page
2. Wait 1-2 sec
3. After closing error popup it pops up again, preventing login

Works fine in chrome, didn't test other FF versions.

layout.css.servo.enabled: true

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