As per summary

So this problem is breaking b-c tests for bug 876926. This is because we drag to the first item in the navbar, and because of some downloads initiated by previous tests, the downloads button got replaced by the indicator. Then because of the social UI resizing tests, we resize the window, and the button ends up in the overflow panel, and then when it comes out it's at the beginning in the navbar because of this bug. When dragging an item onto a skipintoolbarset item, we don't find that item in the placements, and insert it at the end of the navbar (this is a bug we can (and possibly should) fix separately). Because the test expects the item inserted at the beginning rather than at the end, the test fails. This patch only fixes the "don't insert this item at the beginning of the navbar" bug. I can file a followup bug about how our DnD code handles skipintoolbarset items if we think that's worthwhile. And in Cato style, we should be fixing the download-button to not be crazy. :-(

Comment on attachment 805322 [details] [diff] [review] Putting skipintoolbarset items back in the nav-bar should insert at the end, Review of attachment 805322 [details] [diff] [review]: ----------------------------------------------------------------- LGTM!

https://hg.mozilla.org/projects/ux/rev/ba708a4360c4 Thanks for the quick review!