Add "mixed" Flow type
Add "mixed" Flow type

"mixed" is one of the base types listed here:

http://flowtype.org/docs/base-types.html

So this commit adds support for it.

maurobringolf/babel,claudiopro/babel,babel/babylon,claudiopro/babel,babel/babel,PolymerLabs/babel,hulkish/babel,shuhei/babel,maurobringolf/babel,Skillupco/babel,guybedford/babel,hulkish/babel,jridgewell/babel,babel/babel,existentialism/babel,hulkish/babel,kellyselden/babel,kaicataldo/babel,samwgoldman/babel,shuhei/babel,chicoxyzzy/babel,chicoxyzzy/babel,hzoo/babel,guybedford/babel,danez/babylon,PolymerLabs/babel,kaicataldo/babel,babel/babel,existentialism/babel,samwgoldman/babel,PolymerLabs/babel,Skillupco/babel,Skillupco/babel,shuhei/babel,maurobringolf/babel,lightscript/babylon-lightscript,kaicataldo/babel,vadzim/babel,Skillupco/babel,chicoxyzzy/babel,jridgewell/babel,guybedford/babel,jridgewell/babel,kellyselden/babel,claudiopro/babel,chicoxyzzy/babel,hzoo/babel,hulkish/babel,kellyselden/babel,vadzim/babel,kaicataldo/babel,kellyselden/babel,wcjohnson/babylon-lightscript,hzoo/babel,recipesjs/ingredients,hzoo/babel,existentialism/babel,babel/babel,cbishopvelti/babylon,samwgoldman/babel,jridgewell/babel