message: perf(core): prevent iteration of arrays that should not be observable
  close
diff: @@ -157,7 +157,7 @@ export function defineReactive (
  if (childOb) {
  childOb.dep.depend()
  }
  - if (Array.isArray(value)) {
  + if (Array.isArray(value) && Object.isExtensible(value)) {
  dependArray(value)
  }
  }
  