[tsigel]

http://jsfiddle.net/Lzwwz9xd/1/

var tables = parent.querySelectorAll("#pollBlock2 table"),
     div, parent;

Array.prototype.forEach.call(tables, function (table) {
    
    parent = table.parentNode;
    div = document.createElement("DIV");
    div.setAttribute("border", "0");
    parent.appendChild(div);
    div.appendChild(table);

});