Re-merged rev 35ed07abc99e, apparently didn't go through the first time.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>{#table_dlg.merge_cells_title}</title>
<script type="text/javascript" src="../../tiny_mce_popup.js"></script>
<script type="text/javascript" src="../../utils/mctabs.js"></script>
<script type="text/javascript" src="../../utils/validate.js"></script>
<script type="text/javascript" src="js/merge_cells.js"></script>
<base target="_self" />
</head>
<body style="margin: 8px" style="display: none">
<form onsubmit="insertTable();return false;" action="#">
<fieldset>
<legend>{#table_dlg.merge_cells_title}</legend>
<table border="0" cellpadding="0" cellspacing="3" width="100%">
<tr>
<td>{#table_dlg.cols}:</td>
<td align="right"><input type="text" name="numcols" value="" class="number min1" style="width: 30px" /></td>
</tr>
<tr>
<td>{#table_dlg.rows}:</td>
<td align="right"><input type="text" name="numrows" value="" class="number min1" style="width: 30px" /></td>
</tr>
</table>
</fieldset>
<div class="mceActionPanel">
<div style="float: left">
<input type="button" id="insert" name="insert" value="{#update}" onclick="mergeCells();" />
</div>
<div style="float: right">
<input type="button" id="cancel" name="cancel" value="{#cancel}" onclick="tinyMCEPopup.close();" />
</div>
</div>
</form>
</body>
</html>