Moved YGResolveFlexGrow as a method on YGNode

Summary: Moved YGResolveFlexGrow as a method on YGNode

Reviewed By: emilsjolander

Differential Revision: D6611385

fbshipit-source-id: 71660946c469fac77c5ffa0284c793e6adc9db7b

yoga/YGNode.cpp

@@ -421,3 +421,17 @@ void YGNode::markDirtyAndPropogate() {
     }
   }
 }
+
+float YGNode::resolveFlexGrow() {
+  // Root nodes flexGrow should always be 0
+  if (parent_ == nullptr) {
+    return 0.0;
+  }
+  if (!YGFloatIsUndefined(style_.flexGrow)) {
+    return style_.flexGrow;
+  }
+  if (!YGFloatIsUndefined(style_.flex) && style_.flex > 0.0f) {
+    return style_.flex;
+  }
+  return kDefaultFlexGrow;
+}