Default position to NaN

Summary: The position record defaulted to 0, which was wrong. No it defaults to NaN, which is the same as not having a value at all.

Reviewed By: emilsjolander

Differential Revision: D7009783

fbshipit-source-id: 83810da87e983f8d4d3e428f1f5fab0928bce58d

website/src/components/Playground/YogaNode.js

@@ -145,7 +145,7 @@ export default class YogaNode extends Component<Props, State> {
         try {
           root[`set${key[0].toUpperCase()}${key.substr(1)}`](
             yoga[`EDGE_${direction.toUpperCase()}`],
-            layoutDefinition[key][direction] || 0,
+            layoutDefinition[key][direction],
           );
         } catch (e) {}
       });