火狐浏览器表格高度不一致

Question

如果表格中，有空白的，该行的高度明显变大，但如果行中没有空白的，改行高度没有问题。

<table class="tableContent" style="table-layout: fixed;">
    <tr class="userTableLine userTableOne">
        <th><span>用户名</span></th>
        <th class="createTimeticon"><span>部门</span></th>
        <th class="createSpace"><span>角色</span></th>
        <th class="createUtilization"><span>创建时间</span></th>
        <th class="backupTableRight"><span>最后登录时间</span></th>
        <th class="backupTableRight backupTableLeft"><span>状态</span></th>
        <th class="backupTableRight backupTableLeft"><span>操作</span></th>
    </tr>
<tr class="userTableRow" ng-repeat="userList in userLists track by $index">
  <td ui-sref="sidebar.userReview({id: userList.id, name: userList.userName})" class="backupTableRowTd" title="{{userList.userName}}">
<span class="nameWrap">{{userList.userName}}</span>
</td>
<td title="{{userList.deptName}}"><span>{{userList.deptName}}</span></td>
<td title="{{userList.roleInfo.roleName}}"><span class="roleWrap">{{userList.roleInfo.roleName}}</span></td>
<td class="backupTableRowLeft"><span>{{userList.createTime | date:'yyyy-MM-dd HH:mm:ss'}}</span></td>
<td class="backupTableRowLeft"><span>{{userList.lastLoginTime | date:'yyyy-MM-dd HH:mm:ss'}}</span></td>
<td class="userActive"><span ng-if="(userList.userState == 0)" class="userStatusActive">激活</span><span ng-if="(userList.userState == 1)" class="userStatusHang">挂起</span></td>
<td class="userOperate">
  <span ng-show="(userList.userState == 0)">
     <span class="hang diableStyle" title="挂起">挂起</span>
  </span>
  <span ng-show="(userList.userState == 1)">
     <span class="act diableStyle" title="激活">激活</span>
  </span>
  <span class="changeRole diableStyle">更换角色</span>
  <span data-toggle="modal" class="SysAllocate" data-target="#userSysAllocate">分配备份系统</span>
  <span class="seperateLine"></span>
  <i class="icon iconfont icon-delete userManageRemove diableStyle" title="删除"></i>
  <i class="icon iconfont icon-edit userManageEdit diableStyle" title="编辑"></i>
</td>
</tr>
</table>

tr .roleWrap {
    display: inline-block;
    width: 90%;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    vertical-align: bottom;
}
tr .nameWrap{
    display: inline-block;
    width: 80%;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    vertical-align: bottom;
}
tr td {
    color: #3a4b61;
    font-size: 14px;
    height: 44px;
    line-height: 44px;
    text-align: left;
}

但是把高度去掉后，高度却恢复了正常，求原因？