[Fizz] Batch Suspense Boundary Reveal with Throttle (#33076)

Stacked on #33073.

React semantics is that Suspense boundaries reveal with a throttle
(300ms). That helps avoid flashing reveals when a stream reveals many
individual steps back to back. It can also improve overall performance
by batching the layout and paint work that has to happen at each step.

Unfortunately we never implemented this for SSR streaming - only for
client navigations. This is highly noticeable on very dynamic sites with
lots of Suspense boundaries. It can look good with a client nav but feel
glitchy when you reload the page or initial load.

This fixes the Fizz runtime to be throttled and reveals batched into a
single paint at a time. We do this by first tracking the last paint
after the complete (this will be the first paint if `rel="expect"` is
respected). Then in the `completeBoundary` operation we queue the
operation and then flush it all into a throttled batch.

Another motivation is that View Transitions need to operate as a batch
and individual steps get queued in a sequence so it's extra important to
include as much content as possible in each animated step. This will be
done in a follow up for SSR View Transitions.

DiffTrain build for [ee7fee8](ee7fee8)

Author: sebmarkbage

compiled/facebook-www/REVISION

@@ -1 +1 @@
-ee077b6ccddd916440bb7570ba6f53673d920700
+ee7fee8f8875052afde53c5bfc8aedad43ff9d8e

compiled/facebook-www/REVISION_TRANSFORMS

@@ -1 +1 @@
-ee077b6ccddd916440bb7570ba6f53673d920700
+ee7fee8f8875052afde53c5bfc8aedad43ff9d8e

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

@@ -1538,7 +1538,7 @@ __DEV__ &&
     exports.useTransition = function () {
       return resolveDispatcher().useTransition();
     };
-    exports.version = "19.2.0-www-classic-ee077b6c-20250501";
+    exports.version = "19.2.0-www-classic-ee7fee8f-20250501";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

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

@@ -1538,7 +1538,7 @@ __DEV__ &&
     exports.useTransition = function () {
       return resolveDispatcher().useTransition();
     };
-    exports.version = "19.2.0-www-modern-ee077b6c-20250501";
+    exports.version = "19.2.0-www-modern-ee7fee8f-20250501";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

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

@@ -636,4 +636,4 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.2.0-www-classic-ee077b6c-20250501";
+exports.version = "19.2.0-www-classic-ee7fee8f-20250501";

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

@@ -636,4 +636,4 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.2.0-www-modern-ee077b6c-20250501";
+exports.version = "19.2.0-www-modern-ee7fee8f-20250501";

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

@@ -640,7 +640,7 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.2.0-www-classic-ee077b6c-20250501";
+exports.version = "19.2.0-www-classic-ee7fee8f-20250501";
 "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
   "function" ===
     typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

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

@@ -640,7 +640,7 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactSharedInternals.H.useTransition();
 };
-exports.version = "19.2.0-www-modern-ee077b6c-20250501";
+exports.version = "19.2.0-www-modern-ee7fee8f-20250501";
 "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
   "function" ===
     typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

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

@@ -19014,10 +19014,10 @@ __DEV__ &&
     (function () {
       var internals = {
         bundleType: 1,
-        version: "19.2.0-www-classic-ee077b6c-20250501",
+        version: "19.2.0-www-classic-ee7fee8f-20250501",
         rendererPackageName: "react-art",
         currentDispatcherRef: ReactSharedInternals,
-        reconcilerVersion: "19.2.0-www-classic-ee077b6c-20250501"
+        reconcilerVersion: "19.2.0-www-classic-ee7fee8f-20250501"
       };
       internals.overrideHookState = overrideHookState;
       internals.overrideHookStateDeletePath = overrideHookStateDeletePath;
@@ -19051,7 +19051,7 @@ __DEV__ &&
     exports.Shape = Shape;
     exports.Surface = Surface;
     exports.Text = Text;
-    exports.version = "19.2.0-www-classic-ee077b6c-20250501";
+    exports.version = "19.2.0-www-classic-ee7fee8f-20250501";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

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

@@ -18786,10 +18786,10 @@ __DEV__ &&
     (function () {
       var internals = {
         bundleType: 1,
-        version: "19.2.0-www-modern-ee077b6c-20250501",
+        version: "19.2.0-www-modern-ee7fee8f-20250501",
         rendererPackageName: "react-art",
         currentDispatcherRef: ReactSharedInternals,
-        reconcilerVersion: "19.2.0-www-modern-ee077b6c-20250501"
+        reconcilerVersion: "19.2.0-www-modern-ee7fee8f-20250501"
       };
       internals.overrideHookState = overrideHookState;
       internals.overrideHookStateDeletePath = overrideHookStateDeletePath;
@@ -18823,7 +18823,7 @@ __DEV__ &&
     exports.Shape = Shape;
     exports.Surface = Surface;
     exports.Text = Text;
-    exports.version = "19.2.0-www-modern-ee077b6c-20250501";
+    exports.version = "19.2.0-www-modern-ee7fee8f-20250501";
     "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
       "function" ===
         typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&