Set alignItems to ASStackLayoutAlignItemsStretch in ASStackLayoutSpec (#2187)
Set alignItems to ASStackLayoutAlignItemsStretch in ASStackLayoutSpec (#2187)

To align with the CSS `align-items` property we should set alignItems to `ASStackLayoutAlignItemsStretch` instead of `ASStackLayoutAlignItemsStart`: https://drafts.csswg.org/css-flexbox-1/#propdef-align-items
bimawa/AsyncDisplayKit,gazreese/AsyncDisplayKit,maicki/AsyncDisplayKit,rmls/AsyncDisplayKit,JetZou/AsyncDisplayKit,george-gw/AsyncDisplayKit,bimawa/AsyncDisplayKit,samhsiung/AsyncDisplayKit,tomizimobile/AsyncDisplayKit,george-gw/AsyncDisplayKit,JetZou/AsyncDisplayKit,gazreese/AsyncDisplayKit,rahul-malik/AsyncDisplayKit,rahul-malik/AsyncDisplayKit,JetZou/AsyncDisplayKit,george-gw/AsyncDisplayKit,samhsiung/AsyncDisplayKit,rmls/AsyncDisplayKit,tomizimobile/AsyncDisplayKit,tomizimobile/AsyncDisplayKit,tomizimobile/AsyncDisplayKit,romyilano/AsyncDisplayKit,smyrgl/AsyncDisplayKit,Adlai-Holler/AsyncDisplayKit,rahul-malik/AsyncDisplayKit,Adlai-Holler/AsyncDisplayKit,levi/AsyncDisplayKit,chrisdanford/AsyncDisplayKit,chrisdanford/AsyncDisplayKit,aaronschubert0/AsyncDisplayKit,rahul-malik/AsyncDisplayKit,lappp9/AsyncDisplayKit,gazreese/AsyncDisplayKit,levi/AsyncDisplayKit,lappp9/AsyncDisplayKit,maicki/AsyncDisplayKit,bimawa/AsyncDisplayKit,JetZou/AsyncDisplayKit,aaronschubert0/AsyncDisplayKit,aaronschubert0/AsyncDisplayKit,smyrgl/AsyncDisplayKit,flovouin/AsyncDisplayKit,facebook/AsyncDisplayKit,flovouin/AsyncDisplayKit,smyrgl/AsyncDisplayKit,facebook/AsyncDisplayKit,Adlai-Holler/AsyncDisplayKit,levi/AsyncDisplayKit,maicki/AsyncDisplayKit,samhsiung/AsyncDisplayKit,facebook/AsyncDisplayKit,aaronschubert0/AsyncDisplayKit,JetZou/AsyncDisplayKit,george-gw/AsyncDisplayKit,Adlai-Holler/AsyncDisplayKit,lappp9/AsyncDisplayKit,harryworld/AsyncDisplayKit,chrisdanford/AsyncDisplayKit,harryworld/AsyncDisplayKit,levi/AsyncDisplayKit,romyilano/AsyncDisplayKit,flovouin/AsyncDisplayKit,chrisdanford/AsyncDisplayKit,facebook/AsyncDisplayKit,flovouin/AsyncDisplayKit,maicki/AsyncDisplayKit,lappp9/AsyncDisplayKit,gazreese/AsyncDisplayKit,Adlai-Holler/AsyncDisplayKit,rmls/AsyncDisplayKit,aaronschubert0/AsyncDisplayKit,bimawa/AsyncDisplayKit,samhsiung/AsyncDisplayKit,rmls/AsyncDisplayKit,levi/AsyncDisplayKit,harryworld/AsyncDisplayKit,tomizimobile/AsyncDisplayKit,harryworld/AsyncDisplayKit,maicki/AsyncDisplayKit,harryworld/AsyncDisplayKit,romyilano/AsyncDisplayKit,flovouin/AsyncDisplayKit,smyrgl/AsyncDisplayKit,rmls/AsyncDisplayKit,romyilano/AsyncDisplayKit