Maybe file a bug in XPCOM/string about this missing comparison function that you had to implement yourself? I don't know if it is worth fixing, but it is good practice to at least complain "up stream" about missing features.
Bug 1530208 Comment 7 Edit History
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Maybe file a bug in Core::String about this missing comparison function that you had to implement yourself? I don't know if it is worth fixing, but it is good practice to at least complain "up stream" about missing features.