Fix CS0675 warning in c#
Fix CS0675 warning in c#

Summary:
Fix CS0675 warning in c#.
Closes https://github.com/facebook/css-layout/pull/255

Reviewed By: emilsjolander

Differential Revision: D4204765

Pulled By: splhack

fbshipit-source-id: bcf71796e1bf585a94b3549905cb6d6bc78a34b8

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