[hack] Fix container constructors unifying wrong things with each other in case
[hack] Fix container constructors unifying wrong things with each other in case

Summary: One would think that

  $x = $t[0];
  $y = $t[1];

  $v = Vector {$x, $y};

and

  $v = Vector {$t[0], $t[1]};

should be equivalent, but they're currently not - the latter one can change the type of $t[0] and $t[1], while the former can't. I think the first behavior is the intended one.

See unit test telling the story.

Reviewed By: @jwatzman

Differential Revision: D2212534

JohnyDays/flow,fletcherw/flow,chenglou/flow,dv/flow,facebook/flow,shiftcars/flow,ianobermiller/flow,samwgoldman/flow,jeffmo/flow,jeffmo/flow,JonathanUsername/flow,mroch/flow,rafaelstz/flow,nmote/flow,gabelevi/flow,AgentME/flow,lyip1992/flow,facebook/flow,gabro/flow,asivitz/flow,jgrund/flow,popham/flow,ianobermiller/flow,TiddoLangerak/flow,CJstar/flow,matklad/flow,JonathanUsername/flow,facebook/flow,lyip1992/flow,popham/flow,mroch/flow,cesarandreu/flow,shiftcars/flow,fletcherw/flow,OCamlPro/flow,JeckoHeroOrg/flow,davidmason/flow,paulshen/flow,Drooids/flow,samwgoldman/flow,gabelevi/flow,jgrund/flow,ianobermiller/flow,jdelStrother/flow,jgrund/flow,claudiopro/flow,YelaSeamless/flow,jeffmo/flow,davidmason/flow,matklad/flow,darioajr/flow,nmote/flow,jdelStrother/flow,gabelevi/flow,jamesgpearce/flow,siddhartharay007/flow,ForbesLindesay/flow,jgrund/flow,samwgoldman/flow,JonathanUsername/flow,d14b3l/flow,claudiopro/flow,nmote/flow,KevinTCoughlin/flow,mroch/flow,YelaSeamless/flow,KevinTCoughlin/flow,JohnyDays/flow,TiddoLangerak/flow,YelaSeamless/flow,AprilArcus/flow,jeffutter/flow,JonathanUsername/flow,matklad/flow,jamesgpearce/flow,ylu1317/flow,Fresheyeball/flow,Wanderfalke/flow,dv/flow,davidmason/flow,AgentME/flow,shiftcars/flow,Eyyub/flow,jamesgpearce/flow,samwgoldman/flow,jamesgpearce/flow,chenglou/flow,nmote/flow,chenglou/flow,CJstar/flow,dv/flow,claudiopro/flow,graue/flow,Wanderfalke/flow,nmote/flow,shiftcars/flow,gabelevi/flow,jdelStrother/flow,popham/flow,jdelStrother/flow,chenglou/flow,AprilArcus/flow,JeckoHeroOrg/flow,ylu1317/flow,AprilArcus/flow,facebook/flow,paulshen/flow,d14b3l/flow,ForbesLindesay/flow,JeckoHeroOrg/flow,Fresheyeball/flow,Eyyub/flow,Drooids/flow,JeckoHeroOrg/flow,ylu1317/flow,popham/flow,paulshen/flow,MichaelDeBoey/flow,facebook/flow,matklad/flow,siddhartharay007/flow,shiftcars/flow,MichaelDeBoey/flow,shiftcars/flow,d14b3l/flow,TiddoLangerak/flow,graue/flow,paulshen/flow,JohnyDays/flow,MichaelDeBoey/flow,YelaSeamless/flow,graue/flow,d14b3l/flow,ForbesLindesay/flow,AgentME/flow,graue/flow,gabro/flow,cesarandreu/flow,darioajr/flow,gabro/flow,MichaelDeBoey/flow,fletcherw/flow,fletcherw/flow,JonathanUsername/flow,jeffmo/flow,rafaelstz/flow,graue/flow,jdelStrother/flow,asivitz/flow,nmote/flow,Wanderfalke/flow,mcanthony/flow-type,gabelevi/flow,CJstar/flow,ForbesLindesay/flow,jamesgpearce/flow,siddhartharay007/flow,lyip1992/flow,samwgoldman/flow,OCamlPro/flow,gabro/flow,jeffutter/flow,darioajr/flow,Drooids/flow,mroch/flow,ylu1317/flow,Drooids/flow,Fresheyeball/flow,popham/flow,davidmason/flow,AgentME/flow,jeffmo/flow,matklad/flow,d14b3l/flow,JeckoHeroOrg/flow,jgrund/flow,jeffmo/flow,OCamlPro/flow,facebook/flow,danvk/flow,samwgoldman/flow,Eyyub/flow,rafaelstz/flow,danvk/flow,KevinTCoughlin/flow,TiddoLangerak/flow,rafaelstz/flow,ForbesLindesay/flow,mroch/flow,mroch/flow,asivitz/flow,AprilArcus/flow,jgrund/flow,dv/flow,jamesgpearce/flow,CJstar/flow,danvk/flow,cesarandreu/flow,graue/flow,mcanthony/flow-type,jeffutter/flow,asivitz/flow,OCamlPro/flow,ylu1317/flow,siddhartharay007/flow,TiddoLangerak/flow,lyip1992/flow,claudiopro/flow,davidmason/flow,Fresheyeball/flow,YelaSeamless/flow,chenglou/flow,KevinTCoughlin/flow,facebook/flow,popham/flow,Wanderfalke/flow,nmote/flow,samwgoldman/flow,cesarandreu/flow,jdelStrother/flow,JonathanUsername/flow,danvk/flow,Eyyub/flow,fletcherw/flow,rafaelstz/flow,popham/flow,mroch/flow,JonathanUsername/flow,gabelevi/flow,gabro/flow,mcanthony/flow-type,AprilArcus/flow,MichaelDeBoey/flow,claudiopro/flow,AprilArcus/flow,JohnyDays/flow,darioajr/flow,AgentME/flow,jamesgpearce/flow,ForbesLindesay/flow,chenglou/flow,d14b3l/flow,ianobermiller/flow,gabro/flow,mcanthony/flow-type,gabelevi/flow,jeffutter/flow,fletcherw/flow