Fix #10605 - Make File.byLine usable in @safe contexts

[0xEAB]

Implements #10605.

[dlang-bot]

Thanks for your pull request, @0xEAB!

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Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + phobos#10622"

[0xEAB]

Given that this only implements the other half of #10605, I’m not sure whether the commit message (and PR title) should say “Fix #10605”. Let me know, in case you want me to add the prefix.

[rikkimax]

If this PR should close the ticket, add it.

[0xEAB]

If this PR should close the ticket, add it.

Done. Already had it in the commit message’s “body”, but now I’ve added it to the headline.

[0xEAB]

std/stdio.d(2251:9)[warn]: same visibility attribute used as defined on line 2216.

Oh come on, D-Scanner, that one was for readability. But if you insist, I’ll downgrade that one for you…