add unit test for specific scenario where datacontext changes tip before remvoed from visual tree.
add unit test for specific scenario where datacontext changes tip before remvoed from visual tree.

AvaloniaUI/Avalonia,jkoritzinsky/Avalonia,AvaloniaUI/Avalonia,grokys/Perspex,wieslawsoltes/Perspex,wieslawsoltes/Perspex,wieslawsoltes/Perspex,SuperJMN/Avalonia,grokys/Perspex,akrisiun/Perspex,AvaloniaUI/Avalonia,wieslawsoltes/Perspex,SuperJMN/Avalonia,SuperJMN/Avalonia,jkoritzinsky/Perspex,SuperJMN/Avalonia,AvaloniaUI/Avalonia,jkoritzinsky/Avalonia,wieslawsoltes/Perspex,SuperJMN/Avalonia,jkoritzinsky/Avalonia,jkoritzinsky/Avalonia,AvaloniaUI/Avalonia,SuperJMN/Avalonia,jkoritzinsky/Avalonia,wieslawsoltes/Perspex,jkoritzinsky/Avalonia,AvaloniaUI/Avalonia,SuperJMN/Avalonia,AvaloniaUI/Avalonia,Perspex/Perspex,wieslawsoltes/Perspex,jkoritzinsky/Avalonia,Perspex/Perspex