Fabric: Proper traits for `ImageShadowNode` and `ViewShadowNode`

Summary:
* <Image> must be a leaf node; having a proper trait will fail earlier in case of misuse (mounting something inside).
* <View> must have a `View` trait because it's for what that trait is.

Changelog: [Internal] Fabric-specific internal change.

Reviewed By: sammy-SC

Differential Revision: D21028573

fbshipit-source-id: 457716d4661333eb2357f34316f3e495ab4fda24

ReactCommon/fabric/components/image/ImageShadowNode.h

@@ -30,6 +30,12 @@ class ImageShadowNode final : public ConcreteViewShadowNode<
  public:
   using ConcreteViewShadowNode::ConcreteViewShadowNode;
 
+  static ShadowNodeTraits BaseTraits() {
+    auto traits = ConcreteViewShadowNode::BaseTraits();
+    traits.set(ShadowNodeTraits::Trait::LeafYogaNode);
+    return traits;
+  }
+
   /*
    * Associates a shared `ImageManager` with the node.
    */

ReactCommon/fabric/components/view/ViewShadowNode.h

@@ -23,6 +23,12 @@ class ViewShadowNode final : public ConcreteViewShadowNode<
                                  ViewProps,
                                  ViewEventEmitter> {
  public:
+  static ShadowNodeTraits BaseTraits() {
+    auto traits = BaseShadowNode::BaseTraits();
+    traits.set(ShadowNodeTraits::Trait::View);
+    return traits;
+  }
+
   ViewShadowNode(
       ShadowNodeFragment const &fragment,
       ShadowNodeFamily::Shared const &family,