Vue version

@vue/cli 5.0.8

Link to minimal reproduction

null

Steps to reproduce

  <div class="btn-content">
    <el-button >
      <slot></slot>
    </el-button>
  </div>
</template>

 <fs-button  :onclick="handleCancel1">test</fs-button>```
 
 const handleCancel1 = () => {
  console.log(2)
}

Check control trigger handleCancel1

The event is still bound to class = btn-content


### What is expected?

Why

### What is actually happening?

Why

### System Info

```shell
Why

Any additional comments?

No response

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