Bug 913972 - part 0: don't move skipintoolbarset stuff so much, r=mconley (CLOSED TREE)
Bug 913972 - Part 1: Use placements for currentSet so it doesn't reorder because of overflow, r=jaws (CLOSED TREE)
Bug 913972 - Part 2: Add some supporting assertions, r=mconley (CLOSED TREE)
Bug 913972 - Part 3: use placements to reinsert items into toolbar, r=jaws (CLOSED TREE)