Fabric: Refinement of BaseTraits chain

Summary:
Here we refine the `ShadowNode::BaseTraits` static method. Before this change, ConcreteViewShadowNode<> enforces Layoutable and YogaLayoutable traits. This change moves that responsibility to LayoutableShadowNode and YogaLayoutableShadowNode which makes overall logic more coherent.

Changelog: [Internal] Fabric-specific internal change.

Reviewed By: sammy-SC

Differential Revision: D20052027

fbshipit-source-id: fd25264204b0232b1dbbff6f9dfefd9fbcb146c4

Author: shergin

ReactCommon/fabric/components/view/ConcreteViewShadowNode.h

@@ -58,8 +58,6 @@ class ConcreteViewShadowNode : public ConcreteShadowNode<
 
   static ShadowNodeTraits BaseTraits() {
     auto traits = BaseShadowNode::BaseTraits();
-    traits.set(ShadowNodeTraits::Trait::LayoutableKind);
-    traits.set(ShadowNodeTraits::Trait::YogaLayoutableKind);
     traits.set(ShadowNodeTraits::Trait::ViewKind);
     return traits;
   }

ReactCommon/fabric/components/view/yoga/YogaLayoutableShadowNode.cpp

@@ -21,6 +21,12 @@
 namespace facebook {
 namespace react {
 
+ShadowNodeTraits YogaLayoutableShadowNode::BaseTraits() {
+  auto traits = LayoutableShadowNode::BaseTraits();
+  traits.set(ShadowNodeTraits::Trait::YogaLayoutableKind);
+  return traits;
+}
+
 YogaLayoutableShadowNode::YogaLayoutableShadowNode(
     ShadowNodeFragment const &fragment,
     ShadowNodeFamily::Shared const &family,

ReactCommon/fabric/components/view/yoga/YogaLayoutableShadowNode.h

@@ -28,6 +28,8 @@ class YogaLayoutableShadowNode : public LayoutableShadowNode {
       YogaLayoutableShadowNode *,
       kShadowNodeChildrenSmallVectorSize>;
 
+  static ShadowNodeTraits BaseTraits();
+
 #pragma mark - Constructors
 
   YogaLayoutableShadowNode(

ReactCommon/fabric/core/layout/LayoutableShadowNode.cpp

@@ -81,6 +81,12 @@ LayoutableShadowNode::LayoutableShadowNode(
       layoutMetrics_(static_cast<LayoutableShadowNode const &>(sourceShadowNode)
                          .layoutMetrics_) {}
 
+ShadowNodeTraits LayoutableShadowNode::BaseTraits() {
+  auto traits = ShadowNodeTraits{};
+  traits.set(ShadowNodeTraits::Trait::LayoutableKind);
+  return traits;
+}
+
 LayoutMetrics LayoutableShadowNode::getLayoutMetrics() const {
   return layoutMetrics_;
 }

ReactCommon/fabric/core/layout/LayoutableShadowNode.h

@@ -41,6 +41,8 @@ class LayoutableShadowNode : public ShadowNode {
       ShadowNode const &sourceShadowNode,
       ShadowNodeFragment const &fragment);
 
+  static ShadowNodeTraits BaseTraits();
+
   class LayoutInspectingPolicy final {
    public:
     bool includeTransform{true};

ReactCommon/fabric/core/shadownode/ConcreteShadowNode.h

@@ -63,7 +63,7 @@ class ConcreteShadowNode : public BaseShadowNodeT {
    * Reimplement in subclasses to declare class-specific traits.
    */
   static ShadowNodeTraits BaseTraits() {
-    return ShadowNodeTraits{};
+    return BaseShadowNodeT::BaseTraits();
   }
 
   static SharedConcreteProps Props(

ReactCommon/fabric/core/shadownode/ShadowNode.h

@@ -63,6 +63,14 @@ class ShadowNode : public Sealable, public DebugStringConvertible {
    */
   static bool sameFamily(const ShadowNode &first, const ShadowNode &second);
 
+  /*
+   * A set of traits associated with a particular class.
+   * Reimplement in subclasses to declare class-specific traits.
+   */
+  static ShadowNodeTraits BaseTraits() {
+    return ShadowNodeTraits{};
+  }
+
 #pragma mark - Constructors
 
   /*