Move flex basis calculation out into seperate function
Move flex basis calculation out into seperate function

Summary: Move flex basis calculation out into seperate function

Reviewed By: gkassabli

Differential Revision: D4028328

fbshipit-source-id: 6d5f3bf1321077675eaa65408a70c9dc92a675be

facebook/css-layout,yihuang/css-layout,rmarinho/yoga,facebook/css-layout,facebook/css-layout,facebook/yoga,yihuang/css-layout,facebook/css-layout,facebook/yoga,rmarinho/yoga,rmarinho/yoga,yihuang/css-layout,facebook/yoga,yihuang/css-layout,facebook/css-layout,facebook/css-layout,yihuang/css-layout,facebook/yoga,yihuang/css-layout,facebook/yoga,rmarinho/yoga,facebook/yoga,rmarinho/yoga,yihuang/css-layout,yihuang/css-layout,yihuang/css-layout,facebook/css-layout,yihuang/css-layout,facebook/yoga,facebook/yoga,rmarinho/yoga,rmarinho/yoga,facebook/yoga,rmarinho/yoga,rmarinho/yoga,facebook/css-layout,facebook/yoga,rmarinho/yoga,facebook/css-layout