* watch APIs now default to use `flush: 'pre'` instead of
`flush: 'post'`.
- This change affects `watch`, `watchEffect`, the `watch` component
option, and `this.$watch`.
- As pointed out by @skirtles-code in
`flush: 'post'`. This change affects `watch`, `watchEffect`, the `watch` component option, and `this.$watch`. See ([49bb447](https://github.com/vuejs/vue-next/commit/49bb44756fda0a7019c69f2fa6b880d9e41125aa)) for more details.