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/browser/javascript_environment.h

@@ -57,6 +57,8 @@ class NodeEnvironment {
   explicit NodeEnvironment(node::Environment* env);
   ~NodeEnvironment();
 
+  node::Environment* env() { return env_; }
+
  private:
   node::Environment* env_;