firefox: 57.0.3 -> 57.0.4 [High security fix]

[taku0]

Motivation for this change

• Security fixes to address the Meltdown and Spectre timing attacks

https://www.mozilla.org/en-US/firefox/57.0.4/releasenotes/
https://www.mozilla.org/en-US/security/advisories/mfsa2018-01/

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

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