fix: let Node.js perform microtask checkpoint in the main process (#24131)

* fix: let Node.js perform microtask checkpoint in the main process

* fix: don't specify v8::MicrotasksScope for explicit policy

* fix: remove checkpoint from some call-sites

We already perform checkpoint at the end of a task,
either through MicrotaskRunner or through NodeBindings.
There isn't a need to add them again when calling into JS
except when dealing with promises.

* fix: remove checkpoint from some call-sites

We already perform checkpoint at the end of a task,
either through MicrotaskRunner or through NodeBindings.
There isn't a need to add them again when calling into JS
except when dealing with promises.

* fix incorrect specs

* default constructor arguments are considered for explicit mark

* add regression spec

shell/common/gin_helper/microtasks_scope.h

@@ -0,0 +1,31 @@
+// Copyright (c) 2020 GitHub, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#ifndef SHELL_COMMON_GIN_HELPER_MICROTASKS_SCOPE_H_
+#define SHELL_COMMON_GIN_HELPER_MICROTASKS_SCOPE_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "v8/include/v8.h"
+
+namespace gin_helper {
+
+// In the browser process runs v8::MicrotasksScope::PerformCheckpoint
+// In the render process creates a v8::MicrotasksScope.
+class MicrotasksScope {
+ public:
+  explicit MicrotasksScope(v8::Isolate* isolate,
+                           bool ignore_browser_checkpoint = false);
+  ~MicrotasksScope();
+
+ private:
+  std::unique_ptr<v8::MicrotasksScope> v8_microtasks_scope_;
+
+  DISALLOW_COPY_AND_ASSIGN(MicrotasksScope);
+};
+
+}  // namespace gin_helper
+
+#endif  // SHELL_COMMON_GIN_HELPER_MICROTASKS_SCOPE_H_