[v18.x backport] src: use CreateEnvironment instead of inlining its code where possible

src/api/environment.cc

@@ -392,12 +392,13 @@ Environment* CreateEnvironment(
   // options than the global parse call.
   Environment* env = new Environment(
       isolate_data, context, args, exec_args, nullptr, flags, thread_id);
+
 #if HAVE_INSPECTOR
   if (env->should_create_inspector()) {
     if (inspector_parent_handle) {
-      env->InitializeInspector(
-          std::move(static_cast<InspectorParentHandleImpl*>(
-              inspector_parent_handle.get())->impl));
+      env->InitializeInspector(std::move(
+          static_cast<InspectorParentHandleImpl*>(inspector_parent_handle.get())
+              ->impl));
     } else {
       env->InitializeInspector({});
     }

src/node_main_instance.cc

@@ -180,19 +180,8 @@ NodeMainInstance::CreateMainEnvironment(int* exit_code) {
     context = NewContext(isolate_);
     CHECK(!context.IsEmpty());
     Context::Scope context_scope(context);
-    env.reset(new Environment(isolate_data_.get(),
-                              context,
-                              args_,
-                              exec_args_,
-                              nullptr,
-                              EnvironmentFlags::kDefaultFlags,
-                              {}));
-#if HAVE_INSPECTOR
-    env->InitializeInspector({});
-#endif
-    if (env->principal_realm()->RunBootstrapping().IsEmpty()) {
-      return nullptr;
-    }
+    env.reset(
+        CreateEnvironment(isolate_data_.get(), context, args_, exec_args_));
   }
 
   return env;

src/node_snapshotable.cc

@@ -1159,16 +1159,21 @@ int SnapshotBuilder::Generate(SnapshotData* out,
       Context::Scope context_scope(main_context);
 
       // Create the environment.
-      env = new Environment(main_instance->isolate_data(),
-                            main_context,
-                            args,
-                            exec_args,
-                            nullptr,
-                            node::EnvironmentFlags::kDefaultFlags,
-                            {});
-
-      // Run scripts in lib/internal/bootstrap/
-      if (env->principal_realm()->RunBootstrapping().IsEmpty()) {
+      // It's not guaranteed that a context that goes through
+      // v8_inspector::V8Inspector::contextCreated() is runtime-independent,
+      // so do not start the inspector on the main context when building
+      // the default snapshot.
+      uint64_t env_flags = EnvironmentFlags::kDefaultFlags |
+                           EnvironmentFlags::kNoCreateInspector;
+
+      env = CreateEnvironment(main_instance->isolate_data(),
+                              main_context,
+                              args,
+                              exec_args,
+                              static_cast<EnvironmentFlags::Flags>(env_flags));
+
+      // This already ran scripts in lib/internal/bootstrap/, if it fails return
+      if (env == nullptr) {
         return BOOTSTRAP_ERROR;
       }
       // If --build-snapshot is true, lib/internal/main/mksnapshot.js would be