[react-native-renderer] Delete Paper (legacy) renderer (#36285)

## Summary

The Paper renderer is no longer used in React Native. This commit
removes all remaining Paper source code, tests, build system references,
and Paper backward-compatibility branches in shared code.

Deleted Paper-only source files:
- ReactNativeRenderer.js, ReactNativeInjection.js,
ReactFiberConfigNative.js
- ReactNativeComponentTree.js, ReactNativeEventEmitter.js
- ReactNativeFiberHostComponent.js, ReactNativeGlobalResponderHandler.js
- ReactNativeAttributePayload.js, NativeMethodsMixinUtils.js
- ReactFiberConfig.native.js (reconciler fork)
- index.js (Paper entry point)

Cleaned up shared files:
- ReactNativePublicCompat.js: removed _nativeTag checks, UIManager/
legacySendAccessibilityEvent Paper fallbacks
- ReactNativeFiberInspector.js: removed getInspectorDataForViewTag,
UIManager.measure fallback, Paper branch in
getInspectorDataForViewAtPoint
- ReactFiberConfigFabric.js: removed _nativeTag backward compat in
getPublicInstance, removed getInspectorDataForViewTag from devtools
config
- ReactNativeTypes.js: removed ReactNativeType (Paper API type)

Cleaned up build system:
- inlinedHostConfigs.js: removed shortName 'native' config
- forks.js: removed dead 'react-native-renderer' case
- Deleted ReactNative.js shim and Paper-only test mocks

## How did you test this change?

Manually synced the renderer to RN and passed all Fantom tests.

Manually verified the differences in the generated `ReactFabric-dev.js`
file. Only Paper compat logic has been removed.

<details>
<summary>diff</summary> 

```diff
--- /tmp/react-fabric-baseline/ReactFabric-dev.js	2026-04-16 16:42:42
+++ build/react-native/implementations/ReactFabric-dev.js	2026-04-16 18:08:43
@@ -30,43 +30,19 @@
         : emptyObject;
     }
     function createHierarchy(fiberHierarchy) {
-      return fiberHierarchy.map(function (fiber$jscomp$0) {
+      return fiberHierarchy.map(function (fiber) {
         return {
-          name: getComponentNameFromType(fiber$jscomp$0.type),
+          name: getComponentNameFromType(fiber.type),
           getInspectorData: function () {
             return {
-              props: getHostProps(fiber$jscomp$0),
+              props: getHostProps(fiber),
               measure: function (callback) {
-                var hostFiber = findCurrentHostFiber(fiber$jscomp$0);
-                if (
-                  (hostFiber =
-                    null != hostFiber &&
-                    null !== hostFiber.stateNode &&
-                    hostFiber.stateNode.node)
-                )
+                var hostFiber = findCurrentHostFiber(fiber);
+                (hostFiber =
+                  null != hostFiber &&
+                  null !== hostFiber.stateNode &&
+                  hostFiber.stateNode.node) &&
                   nativeFabricUIManager.measure(hostFiber, callback);
-                else {
-                  hostFiber = ReactNativePrivateInterface.UIManager;
-                  var JSCompiler_temp_const = hostFiber.measure,
-                    JSCompiler_inline_result;
-                  a: {
-                    for (var fiber = fiber$jscomp$0; fiber; ) {
-                      null !== fiber.stateNode &&
-                        5 === fiber.tag &&
-                        (JSCompiler_inline_result = findNodeHandle(
-                          fiber.stateNode
-                        ));
-                      if (JSCompiler_inline_result) break a;
-                      fiber = fiber.child;
-                    }
-                    JSCompiler_inline_result = null;
-                  }
-                  return JSCompiler_temp_const.call(
-                    hostFiber,
-                    JSCompiler_inline_result,
-                    callback
-                  );
-                }
               }
             };
           }
@@ -1805,18 +1781,6 @@
       }
       return null;
     }
-    function doesFiberContain(parentFiber, childFiber) {
-      for (
-        var parentFiberAlternate = parentFiber.alternate;
-        null !== childFiber;
-
-      ) {
-        if (childFiber === parentFiber || childFiber === parentFiberAlternate)
-          return !0;
-        childFiber = childFiber.return;
-      }
-      return !1;
-    }
     function traverseVisibleHostChildren(
       child,
       searchWithinHosts,
@@ -16986,44 +16950,6 @@
     function getCurrentFiberForDevTools() {
       return current;
     }
-    function findNodeHandle(componentOrHandle) {
-      var owner = current;
-      null !== owner &&
-        isRendering &&
-        null !== owner.stateNode &&
-        (owner.stateNode._warnedAboutRefsInRender ||
-          console.error(
-            "%s is accessing findNodeHandle inside its render(). render() should be a pure function of props and state. It should never access something that requires stale data from the previous render, such as refs. Move this logic to componentDidMount and componentDidUpdate instead.",
-            getComponentNameFromType(owner.type) || "A component"
-          ),
-        (owner.stateNode._warnedAboutRefsInRender = !0));
-      if (null == componentOrHandle) return null;
-      if ("number" === typeof componentOrHandle) return componentOrHandle;
-      if (componentOrHandle._nativeTag) return componentOrHandle._nativeTag;
-      if (
-        null != componentOrHandle.canonical &&
-        null != componentOrHandle.canonical.nativeTag
-      )
-        return componentOrHandle.canonical.nativeTag;
-      if (
-        (owner =
-          ReactNativePrivateInterface.getNativeTagFromPublicInstance(
-            componentOrHandle
-          ))
-      )
-        return owner;
-      componentOrHandle = findHostInstanceWithWarning(
-        componentOrHandle,
-        "findNodeHandle"
-      );
-      return null == componentOrHandle
-        ? componentOrHandle
-        : null != componentOrHandle._nativeTag
-          ? componentOrHandle._nativeTag
-          : ReactNativePrivateInterface.getNativeTagFromPublicInstance(
-              componentOrHandle
-            );
-    }
     function getNodeFromInternalInstanceHandle(internalInstanceHandle) {
       return (
         internalInstanceHandle &&
@@ -17134,12 +17060,9 @@
         }
         return instance.canonical.publicInstance;
       }
-      return null != instance.containerInfo &&
-        null != instance.containerInfo.publicInstance
+      return null != instance.containerInfo
         ? instance.containerInfo.publicInstance
-        : null != instance._nativeTag
-          ? instance
-          : null;
+        : null;
     }
     function getPublicInstanceFromHostFiber(fiber) {
       fiber = getPublicInstance(fiber.stateNode);
@@ -18017,7 +17940,6 @@
       DefaultEventPriority = 32,
       IdleEventPriority = 268435456,
       searchTarget = null,
-      instanceCache = new Map(),
       bind = Function.prototype.bind,
       valueStack = [];
     var fiberStack = [];
@@ -20041,24 +19963,19 @@
         _nativeFabricUIManage.unstable_getCurrentEventPriority,
       extraDevToolsConfig = {
         getInspectorDataForInstance: getInspectorDataForInstance,
-        getInspectorDataForViewTag: function (viewTag) {
-          viewTag = instanceCache.get(viewTag) || null;
-          return getInspectorDataForInstance(viewTag);
-        },
         getInspectorDataForViewAtPoint: function (
           inspectedView,
           locationX,
           locationY,
           callback
         ) {
-          var closestInstance = null,
-            fabricNode =
-              ReactNativePrivateInterface.getNodeFromPublicInstance(
-                inspectedView
-              );
-          fabricNode
+          var closestInstance = null;
+          (inspectedView =
+            ReactNativePrivateInterface.getNodeFromPublicInstance(
+              inspectedView
+            ))
             ? nativeFabricUIManager.findNodeAtPoint(
-                fabricNode,
+                inspectedView,
                 locationX,
                 locationY,
                 function (internalInstanceHandle) {
@@ -20109,32 +20026,9 @@
                   }
                 }
               )
-            : null != inspectedView._internalFiberInstanceHandleDEV
-              ? ReactNativePrivateInterface.UIManager.findSubviewIn(
-                  findNodeHandle(inspectedView),
-                  [locationX, locationY],
-                  function (nativeViewTag, left, top, width, height) {
-                    var inspectorData = getInspectorDataForInstance(
-                      instanceCache.get(nativeViewTag) || null
-                    );
-                    callback(
-                      assign({}, inspectorData, {
-                        pointerY: locationY,
-                        frame: {
-                          left: left,
-                          top: top,
-                          width: width,
-                          height: height
-                        },
-                        touchedViewTag: nativeViewTag,
-                        closestPublicInstance: nativeViewTag
-                      })
-                    );
-                  }
-                )
-              : console.error(
-                  "getInspectorDataForViewAtPoint expects to receive a host component"
-                );
+            : console.error(
+                "getInspectorDataForViewAtPoint expects to receive a host component"
+              );
         }
       },
       getViewConfigForType =
@@ -20368,23 +20262,12 @@
       );
     };
     exports.dispatchCommand = function (handle, command, args) {
-      var nativeTag =
-        null != handle._nativeTag
-          ? handle._nativeTag
-          : ReactNativePrivateInterface.getNativeTagFromPublicInstance(handle);
-      null == nativeTag
-        ? console.error(
+      handle = ReactNativePrivateInterface.getNodeFromPublicInstance(handle);
+      null != handle
+        ? nativeFabricUIManager.dispatchCommand(handle, command, args)
+        : console.error(
             "dispatchCommand was called with a ref that isn't a native component. Use React.forwardRef to get access to the underlying native component"
-          )
-        : ((handle =
-            ReactNativePrivateInterface.getNodeFromPublicInstance(handle)),
-          null != handle
-            ? nativeFabricUIManager.dispatchCommand(handle, command, args)
-            : ReactNativePrivateInterface.UIManager.dispatchViewManagerCommand(
-                nativeTag,
-                command,
-                args
-              ));
+          );
     };
     exports.findHostInstance_DEPRECATED = function (componentOrHandle) {
       var owner = current;
@@ -20402,14 +20285,46 @@
         : componentOrHandle.canonical &&
             componentOrHandle.canonical.publicInstance
           ? componentOrHandle.canonical.publicInstance
-          : componentOrHandle._nativeTag
-            ? componentOrHandle
-            : findHostInstanceWithWarning(
-                componentOrHandle,
-                "findHostInstance_DEPRECATED"
-              );
+          : findHostInstanceWithWarning(
+              componentOrHandle,
+              "findHostInstance_DEPRECATED"
+            );
     };
-    exports.findNodeHandle = findNodeHandle;
+    exports.findNodeHandle = function (componentOrHandle) {
+      var owner = current;
+      null !== owner &&
+        isRendering &&
+        null !== owner.stateNode &&
+        (owner.stateNode._warnedAboutRefsInRender ||
+          console.error(
+            "%s is accessing findNodeHandle inside its render(). render() should be a pure function of props and state. It should never access something that requires stale data from the previous render, such as refs. Move this logic to componentDidMount and componentDidUpdate instead.",
+            getComponentNameFromType(owner.type) || "A component"
+          ),
+        (owner.stateNode._warnedAboutRefsInRender = !0));
+      if (null == componentOrHandle) return null;
+      if ("number" === typeof componentOrHandle) return componentOrHandle;
+      if (
+        null != componentOrHandle.canonical &&
+        null != componentOrHandle.canonical.nativeTag
+      )
+        return componentOrHandle.canonical.nativeTag;
+      if (
+        (owner =
+          ReactNativePrivateInterface.getNativeTagFromPublicInstance(
+            componentOrHandle
+          ))
+      )
+        return owner;
+      componentOrHandle = findHostInstanceWithWarning(
+        componentOrHandle,
+        "findNodeHandle"
+      );
+      return null == componentOrHandle
+        ? componentOrHandle
+        : ReactNativePrivateInterface.getNativeTagFromPublicInstance(
+            componentOrHandle
+          );
+    };
     exports.getNodeFromInternalInstanceHandle =
       getNodeFromInternalInstanceHandle;
     exports.getPublicInstanceFromInternalInstanceHandle = function (
@@ -20433,14 +20348,6 @@
         : null;
     };
     exports.isChildPublicInstance = function (parentInstance, childInstance) {
-      if (
-        parentInstance._internalFiberInstanceHandleDEV &&
-        childInstance._internalFiberInstanceHandleDEV
-      )
-        return doesFiberContain(
-          parentInstance._internalFiberInstanceHandleDEV,
-          childInstance._internalFiberInstanceHandleDEV
-        );
       parentInstance =
         ReactNativePrivateInterface.getInternalInstanceHandleFromPublicInstance(
           parentInstance
@@ -20449,9 +20356,27 @@
         ReactNativePrivateInterface.getInternalInstanceHandleFromPublicInstance(
           childInstance
         );
-      return null != parentInstance && null != childInstance
-        ? doesFiberContain(parentInstance, childInstance)
-        : !1;
+      if (null != parentInstance && null != childInstance) {
+        a: {
+          for (
+            var parentFiberAlternate = parentInstance.alternate;
+            null !== childInstance;
+
+          ) {
+            if (
+              childInstance === parentInstance ||
+              childInstance === parentFiberAlternate
+            ) {
+              parentInstance = !0;
+              break a;
+            }
+            childInstance = childInstance.return;
+          }
+          parentInstance = !1;
+        }
+        return parentInstance;
+      }
+      return !1;
     };
     exports.render = function (
       element,
@@ -20521,22 +20446,12 @@
       return element;
     };
     exports.sendAccessibilityEvent = function (handle, eventType) {
-      var nativeTag =
-        null != handle._nativeTag
-          ? handle._nativeTag
-          : ReactNativePrivateInterface.getNativeTagFromPublicInstance(handle);
-      null == nativeTag
-        ? console.error(
+      handle = ReactNativePrivateInterface.getNodeFromPublicInstance(handle);
+      null != handle
+        ? nativeFabricUIManager.sendAccessibilityEvent(handle, eventType)
+        : console.error(
             "sendAccessibilityEvent was called with a ref that isn't a native component. Use React.forwardRef to get access to the underlying native component"
-          )
-        : ((handle =
-            ReactNativePrivateInterface.getNodeFromPublicInstance(handle)),
-          null != handle
-            ? nativeFabricUIManager.sendAccessibilityEvent(handle, eventType)
-            : ReactNativePrivateInterface.legacySendAccessibilityEvent(
-                nativeTag,
-                eventType
-              ));
+          );
     };
     exports.stopSurface = function (containerTag) {
       var root = roots.get(containerTag);
```

</details>

Author: rubennorte

packages/react-native-renderer/index.js

@@ -66,7 +66,6 @@ import {getClosestInstanceFromNode} from './ReactFabricComponentTree';
 import {compareDocumentPositionForEmptyFragment} from 'shared/ReactDOMFragmentRefShared';
 
 import {
-  getInspectorDataForViewTag,
   getInspectorDataForViewAtPoint,
   getInspectorDataForInstance,
 } from './ReactNativeFiberInspector';
@@ -79,7 +78,6 @@ export {default as rendererVersion} from 'shared/ReactVersion'; // TODO: Conside
 export const rendererPackageName = 'react-native-renderer';
 export const extraDevToolsConfig = {
   getInspectorDataForInstance,
-  getInspectorDataForViewTag,
   getInspectorDataForViewAtPoint,
 };
 
@@ -142,8 +140,6 @@ export type TransitionStatus = mixed;
 
 export type RendererInspectionConfig = $ReadOnly<{
   getInspectorDataForInstance?: (instance: Fiber | null) => InspectorData,
-  // Deprecated. Replaced with getInspectorDataForViewAtPoint.
-  getInspectorDataForViewTag?: (tag: number) => Object,
   getInspectorDataForViewAtPoint?: (
     inspectedView: Object,
     locationX: number,
@@ -313,17 +309,7 @@ export function getPublicInstance(instance: Instance): null | PublicInstance {
 
   // Handle root containers
   if (instance.containerInfo != null) {
-    if (instance.containerInfo.publicInstance != null) {
-      return instance.containerInfo.publicInstance;
-    }
-  }
-
-  // For compatibility with the legacy renderer, in case it's used with Fabric
-  // in the same app.
-  // $FlowExpectedError[prop-missing]
-  if (instance._nativeTag != null) {
-    // $FlowExpectedError[incompatible-return]
-    return instance;
+    return instance.containerInfo.publicInstance;
   }
 
   return null;