element-ui,tab-position設(shè)置不生效

element-ui版本：1.4.9
官方例子：也不生效

  <template>
                <el-radio-group v-model="tabPosition" style="margin-bottom: 30px;">
                    <el-radio-button label="top">top</el-radio-button>
                    <el-radio-button label="right">right</el-radio-button>
                    <el-radio-button label="bottom">bottom</el-radio-button>
                    <el-radio-button label="left">left</el-radio-button>
                </el-radio-group>

                <el-tabs :tab-position="tabPosition" style="height: 200px;">
                    <el-tab-pane label="User">User</el-tab-pane>
                    <el-tab-pane label="Config">Config</el-tab-pane>
                    <el-tab-pane label="Role">Role</el-tab-pane>
                    <el-tab-pane label="Task">Task</el-tab-pane>
                </el-tabs>
  </template>