Add JavaScript bindings for YGHasNewLayout (#1631)

Summary:
Adds JavaScript bindings for YGHasNewLayout which introduces
two new node methods: `hasNewLayout()` and `markLayoutSeen()`.

Closes https://github.com/facebook/yoga/issues/681

Pull Request resolved: https://github.com/facebook/yoga/pull/1631

Reviewed By: joevilches

Differential Revision: D55213296

Pulled By: NickGerleman

fbshipit-source-id: 161288c3f54c2b82a6b2b842387916fe8713c2c9

javascript/src/Node.h

@@ -195,6 +195,8 @@ class Node {
  public: // Dirtiness accessors
   void markDirty(void);
   bool isDirty(void) const;
+  void markLayoutSeen();
+  bool hasNewLayout(void) const;
 
  public: // Layout mutators
   void calculateLayout(double width, double height, int direction);