code: function jscoverage_selectTab(tab) {
    if (typeof tab !== 'number') {
      tab = jscoverage_tabIndexOf(tab);
    }
    var tabs = document.getElementById('tabs');
    var tabPages = document.getElementById('tabPages');
    var nodeList;
    var tabNum;
    var i;
    var node;
  
    nodeList = tabs.childNodes;
    tabNum = 0;
    for (i = 0; i < nodeList.length; i++) {
      node = nodeList.item(i);
      if (node.nodeType !== 1) {
        continue;
      }
  
      if (node.className !== 'disabled') {
        if (tabNum === tab) {
          node.className = 'selected';
        }
        else {
          node.className = '';
        }
      }
      tabNum++;
    }
  
    nodeList = tabPages.childNodes;
    tabNum = 0;
    for (i = 0; i < nodeList.length; i++) {
      node = nodeList.item(i);
      if (node.nodeType !== 1) {
        continue;
      }
  
      if (tabNum === tab) {
        node.className = 'selected TabPage';
      }
      else {
        node.className = 'TabPage';
      }
      tabNum++;
    }
  }
docs: Selects a tab.
  @param  tab  the integer index of the tab (0, 1, 2, or 3)
  OR
  the ID of the tab element
  OR
  the tab element itself