fix 清空v-model绑定的值(赋值为[]时),界面显示上不生效的问题

[songyazhao]

触发该问题的例子:

<template>
  <div>
    <al-cascader v-model="area"/>
    <button @click="handleCleanArea"></button>
  </div>
</template>

<script>
export default {
  data() {
    area: [
      "120000",
      "120100",
      "120101",
      "120101001000"
    ]
  },
  methods: {
    handleCleanArea() {
      // 此处对area清空时并不会触发el-cascader组件的视图更新
      this.area = []
    }
  }
}
</script>

[init-object]

No compatible version found: iview-area@^1.5.18
Valid install targets: 1.5.17, 1.5.16, 1.5.15, 1.5.14, 1.5.13,

[songyazhao]

没办法，只能等待作者合并，然后发布1.5.18