element 树形菜单加title

<script src="//unpkg.com/vue/dist/vue.js"></script>
<script src="//unpkg.com/element-ui@2.5.4/lib/index.js"></script>
<div id="app">
<el-tree :data="data" :props="defaultProps" @node-click="handleNodeClick">
<span class="span-ellipsis" slot-scope="{ node, data }">
<span :title="node.label">{{ node.label }}</span>
</span>

</el-tree>
</div>