deps: V8: backport 4bf051d536a1

Original commit message:

    [api] Add Context::GetMicrotaskQueue method

    Add a method that returns the microtask queue that is being used
    by the `v8::Context`.

    This is helpful in non-monolithic embedders like Node.js, which
    accept Contexts created by its own embedders like Electron, or
    for native Node.js addons. In particular, it enables:

    1. Making sure that “nested” `Context`s use the correct microtask
       queue, i.e. the one from the outer Context.
    2. Enqueueing microtasks into the correct microtask queue.

    Previously, these things only worked when the microtask queue for
    a given Context was the Isolate’s default queue.

    As an alternative, I considered adding a way to make new `Context`s
    inherit the queue from the `Context` that was entered at the time
    of their creation, but that seemed a bit more “magic”, less flexible,
    and didn’t take care of concern 2 listed above.

    Change-Id: I15ed796df90f23c97a545a8e1b30a3bf4a5c4320
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2579914
    Reviewed-by: Toon Verwaest <verwaest@chromium.org>
    Commit-Queue: Toon Verwaest <verwaest@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#71710}

Refs: 4bf051d536

PR-URL: https://github.com/nodejs/node/pull/36482
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

common.gypi

@@ -36,7 +36,7 @@
 
     # Reset this number to 0 on major V8 upgrades.
     # Increment by one for each non-official patch applied to deps/v8.
-    'v8_embedder_string': '-node.20',
+    'v8_embedder_string': '-node.21',
 
     ##### V8 defaults for Node.js #####
 

deps/v8/include/v8.h

@@ -10417,9 +10417,12 @@ class V8_EXPORT Context {
    */
   void Exit();
 
-  /** Returns an isolate associated with a current context. */
+  /** Returns the isolate associated with a current context. */
   Isolate* GetIsolate();
 
+  /** Returns the microtask queue associated with a current context. */
+  MicrotaskQueue* GetMicrotaskQueue();
+
   /**
    * The field at kDebugIdIndex used to be reserved for the inspector.
    * It now serves no purpose.

deps/v8/src/api/api.cc

@@ -6118,6 +6118,12 @@ v8::Isolate* Context::GetIsolate() {
   return reinterpret_cast<Isolate*>(env->GetIsolate());
 }
 
+v8::MicrotaskQueue* Context::GetMicrotaskQueue() {
+  i::Handle<i::Context> env = Utils::OpenHandle(this);
+  CHECK(env->IsNativeContext());
+  return i::Handle<i::NativeContext>::cast(env)->microtask_queue();
+}
+
 v8::Local<v8::Object> Context::Global() {
   i::Handle<i::Context> context = Utils::OpenHandle(this);
   i::Isolate* isolate = context->GetIsolate();

deps/v8/test/cctest/test-api.cc

@@ -28348,3 +28348,13 @@ TEST(TriggerThreadSafeMetricsEvent) {
   CHECK_EQ(recorder->count_, 1);  // Increased.
   CHECK_EQ(recorder->module_count_, 42);
 }
+
+THREADED_TEST(MicrotaskQueueOfContext) {
+  auto microtask_queue = v8::MicrotaskQueue::New(CcTest::isolate());
+  v8::HandleScope scope(CcTest::isolate());
+  v8::Local<Context> context = Context::New(
+      CcTest::isolate(), nullptr, v8::MaybeLocal<ObjectTemplate>(),
+      v8::MaybeLocal<Value>(), v8::DeserializeInternalFieldsCallback(),
+      microtask_queue.get());
+  CHECK_EQ(context->GetMicrotaskQueue(), microtask_queue.get());
+}