Auto merge of #18102 - hiikezoe:compute-distance-for-shadow-list, r=boris
Auto merge of #18102 - hiikezoe:compute-distance-for-shadow-list, r=boris

Implement distance for shadow list.

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https://bugzilla.mozilla.org/show_bug.cgi?id=1387973
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors

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