workaround to fix about:safebrowsing redirect

[diracdeltas]

fix #8905. this is a workaround for the underlying issue, which is that the l20n.min.js resource is blocked when about:safebrowsing is redirected to from a remote page instead of loaded directly.

Test Plan:

1. safebrowsing test should pass
2. go to downloadme.org. it should redirect to the safebrowsing page and the page should not be blank or have missing text.

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).

Test Plan:

Reviewer Checklist:

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[luixxiul]

Both manual test plan and automated test work. LGTM.

[NejcZdovc]

LGTM

[NejcZdovc]

side note @luixxiul could you please fix this one, I saw it while testing this PR. Button is jumping around 😄

[bbondy]

++