implement multiple slot? You can"t name slot name yourself
<el-pagination :page-sizes="[100, 200, 300, 400]" :page-size="100" @current-change="handleCurrentChange" :current-page.sync="currentPage" layout="sizes, slot, prev, pager, next, slot, total" :total="1000" popper-class="pagination">
<span class="first"></span>
<span class="last"></span>
</el-pagination>