refactor: use markRaw instead of internal flag check

packages/runtime-core/src/component.ts

@@ -4,7 +4,8 @@ import {
   pauseTracking,
   resetTracking,
   shallowReadonly,
-  proxyRefs
+  proxyRefs,
+  markRaw
 } from '@vue/reactivity'
 import {
   ComponentPublicInstance,
@@ -597,7 +598,7 @@ function setupStatefulComponent(
   instance.accessCache = Object.create(null)
   // 1. create public instance / render proxy
   // also mark it raw so it's never observed
-  instance.proxy = new Proxy(instance.ctx, PublicInstanceProxyHandlers)
+  instance.proxy = markRaw(new Proxy(instance.ctx, PublicInstanceProxyHandlers))
   if (__DEV__) {
     exposePropsOnRenderContext(instance)
   }