New children notify fragment instances in Fabric (#33093)

When a new child of a fragment instance is inserted, we need to notify
the instance to keep any relevant tracking up to date. For example, we
automatically observe the new child with any active
IntersectionObserver.

For mutable renderers (DOM), we reuse the existing traversal in
`commitPlacement` that does the insertions for HostComponents. Immutable
renderers (Fabric) exit this path before the traversal though, so
currently we can't notify the fragment instances.

Here I've created a separate traversal in `commitPlacement`,
specifically for immutable renders when `enableFragmentRefs` is on.

DiffTrain build for [1835b3f](1835b3f)

Author: jackpope

compiled/facebook-www/REVISION

@@ -1 +1 @@
-f4041aa388b7eeba94a26f6c273e9f4c18e2d2b3
+1835b3f7d9c0541259a8812c5dfaf3d77f0721eb

compiled/facebook-www/REVISION_TRANSFORMS

@@ -1 +1 @@
-f4041aa388b7eeba94a26f6c273e9f4c18e2d2b3
+1835b3f7d9c0541259a8812c5dfaf3d77f0721eb

compiled/facebook-www/React-dev.classic.js

@@ -1537,7 +1537,7 @@ __DEV__ &&
     exports.useTransition = function () {
       return resolveDispatcher().useTransition();
     };
-    exports.version = "19.2.0-www-classic-f4041aa3-20250521";
+    exports.version = "19.2.0-www-classic-1835b3f7-20250521";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/React-dev.modern.js

@@ -1537,7 +1537,7 @@ __DEV__ &&
     exports.useTransition = function () {
       return resolveDispatcher().useTransition();
     };
-    exports.version = "19.2.0-www-modern-f4041aa3-20250521";
+    exports.version = "19.2.0-www-modern-1835b3f7-20250521";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/React-prod.classic.js

@@ -635,4 +635,4 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.2.0-www-classic-f4041aa3-20250521";
+exports.version = "19.2.0-www-classic-1835b3f7-20250521";

compiled/facebook-www/React-prod.modern.js

@@ -635,4 +635,4 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.2.0-www-modern-f4041aa3-20250521";
+exports.version = "19.2.0-www-modern-1835b3f7-20250521";

compiled/facebook-www/React-profiling.classic.js

@@ -639,7 +639,7 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.2.0-www-classic-f4041aa3-20250521";
+exports.version = "19.2.0-www-classic-1835b3f7-20250521";
 "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
   "function" ===
     typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/React-profiling.modern.js

@@ -639,7 +639,7 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.2.0-www-modern-f4041aa3-20250521";
+exports.version = "19.2.0-www-modern-1835b3f7-20250521";
 "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
   "function" ===
     typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/ReactART-dev.classic.js

@@ -19080,10 +19080,10 @@ __DEV__ &&
     (function () {
       var internals = {
         bundleType: 1,
-        version: "19.2.0-www-classic-f4041aa3-20250521",
+        version: "19.2.0-www-classic-1835b3f7-20250521",
         rendererPackageName: "react-art",
         currentDispatcherRef: ReactSharedInternals,
-        reconcilerVersion: "19.2.0-www-classic-f4041aa3-20250521"
+        reconcilerVersion: "19.2.0-www-classic-1835b3f7-20250521"
       };
       internals.overrideHookState = overrideHookState;
       internals.overrideHookStateDeletePath = overrideHookStateDeletePath;
@@ -19117,7 +19117,7 @@ __DEV__ &&
     exports.Shape = Shape;
     exports.Surface = Surface;
     exports.Text = Text;
-    exports.version = "19.2.0-www-classic-f4041aa3-20250521";
+    exports.version = "19.2.0-www-classic-1835b3f7-20250521";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled/facebook-www/ReactART-dev.modern.js

@@ -18852,10 +18852,10 @@ __DEV__ &&
     (function () {
       var internals = {
         bundleType: 1,
-        version: "19.2.0-www-modern-f4041aa3-20250521",
+        version: "19.2.0-www-modern-1835b3f7-20250521",
         rendererPackageName: "react-art",
         currentDispatcherRef: ReactSharedInternals,
-        reconcilerVersion: "19.2.0-www-modern-f4041aa3-20250521"
+        reconcilerVersion: "19.2.0-www-modern-1835b3f7-20250521"
       };
       internals.overrideHookState = overrideHookState;
       internals.overrideHookStateDeletePath = overrideHookStateDeletePath;
@@ -18889,7 +18889,7 @@ __DEV__ &&
     exports.Shape = Shape;
     exports.Surface = Surface;
     exports.Text = Text;
-    exports.version = "19.2.0-www-modern-f4041aa3-20250521";
+    exports.version = "19.2.0-www-modern-1835b3f7-20250521";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&