It seems [this test](https://searchfox.org/mozilla-central/rev/dd042f25a8da58d565d199dcfebe4f34db64863c/layout/generic/test/test_bug496275.html) is the only use of the attribute. It doesn't sound like a very good reason to keep it at all, maybe we could just remove it and modify the test 🤔
Bug 1623290 Comment 5 Edit History
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It seems [this test](https://searchfox.org/mozilla-central/rev/dd042f25a8da58d565d199dcfebe4f34db64863c/layout/generic/test/test_bug496275.html) is the only use of the attribute. It doesn't sound like a very good reason to keep it at all, maybe we could just remove it and modify the test 🤔 Edit: I guess https://github.com/ProseMirror/prosemirror/issues/960 needs to be investigated so that it won't regress by the removal.