[platform] Require the foreground taskrunner to support non-nestable tasks for weak refs

Bug: v8:8179
Change-Id: I2e7024412216decc06e814e88eecd5b4eb5ae8cb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2013696
Reviewed-by: Ben Smith <binji@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65966}

include/v8-platform.h

@@ -326,7 +326,8 @@ class Platform {
 
   /**
    * Returns a TaskRunner which can be used to post a task on the foreground.
-   * This function should only be called from a foreground thread.
+   * The TaskRunner's NonNestableTasksEnabled() must be true. This function
+   * should only be called from a foreground thread.
    */
   virtual std::shared_ptr<v8::TaskRunner> GetForegroundTaskRunner(
       Isolate* isolate) = 0;

src/api/api.cc

@@ -8269,6 +8269,14 @@ void Isolate::Initialize(Isolate* isolate,
   }
   i_isolate->set_only_terminate_in_safe_scope(
       params.only_terminate_in_safe_scope);
+
+  if (!i::V8::GetCurrentPlatform()
+           ->GetForegroundTaskRunner(isolate)
+           ->NonNestableTasksEnabled()) {
+    FATAL(
+        "The current platform's foreground task runner does not have "
+        "non-nestable tasks enabled. The embedder must provide one.");
+  }
 }
 
 Isolate* Isolate::New(const Isolate::CreateParams& params) {

src/d8/d8-platforms.cc

@@ -175,6 +175,11 @@ class DelayedTasksPlatform : public Platform {
       task_runner_->PostTask(platform_->MakeDelayedTask(std::move(task)));
     }
 
+    void PostNonNestableTask(std::unique_ptr<Task> task) final {
+      task_runner_->PostNonNestableTask(
+          platform_->MakeDelayedTask(std::move(task)));
+    }
+
     void PostDelayedTask(std::unique_ptr<Task> task,
                          double delay_in_seconds) final {
       task_runner_->PostDelayedTask(platform_->MakeDelayedTask(std::move(task)),
@@ -188,6 +193,10 @@ class DelayedTasksPlatform : public Platform {
 
     bool IdleTasksEnabled() final { return task_runner_->IdleTasksEnabled(); }
 
+    bool NonNestableTasksEnabled() const final {
+      return task_runner_->NonNestableTasksEnabled();
+    }
+
    private:
     friend class DelayedTaskRunnerDeleter;
     std::shared_ptr<TaskRunner> task_runner_;

test/unittests/compiler-dispatcher/compiler-dispatcher-unittest.cc

@@ -272,6 +272,11 @@ class MockPlatform : public v8::Platform {
       platform_->foreground_tasks_.push_back(std::move(task));
     }
 
+    void PostNonNestableTask(std::unique_ptr<v8::Task> task) override {
+      // The mock platform does not nest tasks.
+      PostTask(std::move(task));
+    }
+
     void PostDelayedTask(std::unique_ptr<Task> task,
                          double delay_in_seconds) override {
       UNREACHABLE();
@@ -286,6 +291,8 @@ class MockPlatform : public v8::Platform {
 
     bool IdleTasksEnabled() override { return true; }
 
+    bool NonNestableTasksEnabled() const override { return false; }
+
    private:
     MockPlatform* platform_;
   };