use muon's IP address check instead of node's

[diracdeltas]

partial fix for #10825 (noscript allowing scripts when host is an ipv6 address)

Test Plan:

1. npm run test -- --grep='can allow scripts when the url host is an ipv6 address' (the test is skipped on travis due to lack of ipv6 support)

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).
• Tagged reviewers and labelled the pull request as 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

[evq]

lgtm