Failing with CSP under current versions of Firefox

[kitsonk]

Bug

There has been a regression of the loader apparently failing in a CSP mode when running under current versions of Firefox.

[kitsonk]

When I run grunt test:remote from the CLI on my machine, and these issues do not occur.

× firefox on WINDOWS - AMD loading with CSP enabled - simple (2.725s)
× firefox on WINDOWS - AMD loading with CSP enabled - cdn (1.474s)

[kitsonk]

It does appear though that pinning Firefox to the ESR version 52 does resolve the problem. Might as well do that.