message: fix(transition): fix out-in transition getting stuck with v-if
  fix
diff: @@ -161,7 +161,9 @@ export default {
  oldChild &&
  oldChild.data &&
  !isSameChild(child, oldChild) &&
  - !isAsyncPlaceholder(oldChild)
  + !isAsyncPlaceholder(oldChild) &&
  + // #6687 component root is a comment node
  + !(oldChild.componentInstance && oldChild.componentInstance._vnode.isComment)
  ) {
  // replace old child transition data with fresh one
  // important for dynamic transitions!
  