Filing this bug on finishing off / landing patch 8 in bug 735898, to remove the secondary content-order sort when we're sorting display-lists by z-index.
For background, see bug 735898 comment 50 & beyond.
Actually, it looks like bug 748646 is already filed as a followup on this.
*** This bug has been marked as a duplicate of bug 748646 ***
Actually, I shouldn't have duped this -- this bug isn't really a duplicate of bug 772690 -- it just depends on it.
That bugs' patches are now landed (on m-i), so the content-order-sort in SortByZOrder can now land without causing orange.
So, I'll land the SortByZOrder tweak in this bug. (simply using the changeset for part 8 from bug 735898, but with commit-message updated to point to this bug instead of that one)
Created attachment 644938 [details] [diff] [review]
fix [r=dbaron granted in bug 735898 comment 47]
Here's the patch (review already granted in bug 735898 comment 47)