https://bugzilla.mozilla.org/show_bug.cgi?id=810274 Bug 810274 seems to have inserted this check and explains the background in detail regarding sub-pixel scroll. Now that we have a new drawing engine, maybe the situation could improve.
Bug 1695139 Comment 3 Edit History
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https://bugzilla.mozilla.org/show_bug.cgi?id=810274 Bug 810274 seems to have inserted this check and explains the background in detail regarding sub-pixel scroll. Now that we have a new drawing engine, maybe the situation could improve. Anyway, more than 3K warnings during a test run seems a bit excessive, and one wonders naturally what goes on.