Add Overflow API.

Summary: We need this for scrollviews, bring on the overflow!

Reviewed By: emilsjolander

Differential Revision: D4376759

fbshipit-source-id: a427432da5e8679dbf9fdbfe4250707e727368f4

YogaKit/UIView+Yoga.m

@@ -130,6 +130,11 @@
   YGNodeStyleSetFlexWrap([self ygNode], flexWrap);
 }
 
+- (void)yg_setOverflow:(YGOverflow)overflow
+{
+  YGNodeStyleSetOverflow([self ygNode], overflow);
+}
+
 - (void)yg_setFlexGrow:(CGFloat)flexGrow
 {
   YGNodeStyleSetFlexGrow([self ygNode], flexGrow);