Fix some problems in the documentation.

lib/OpenLayers/Util.js

@@ -933,7 +933,7 @@ OpenLayers.Util.lastSeqID = 0;
  *     prefix (defaults to "id_") appended with the counter value.
  * 
  * Parameters:
- * prefix {String} Optionsal string to prefix unique id. Default is "id_".
+ * prefix - {String} Optional string to prefix unique id. Default is "id_".
  * 
  * Returns:
  * {String} A unique id string, built on the passed in prefix.
@@ -1250,6 +1250,9 @@ OpenLayers.Util.pagePosition =  function(forElement) {
  * document.body or document.documentElement, depending on the document's
  * compatibility mode (see
  * http://code.google.com/p/doctype/wiki/ArticleClientViewportElement)
+ *
+ * Returns:
+ * {DOMElement}
  */
 OpenLayers.Util.getViewportElement = function() {
     var viewportElement = arguments.callee.viewportElement;