Fix proposed for sidebar widget code to be HTML5 compliant

[gfitzp]

Using the code from the ​Widgetizing Themes tutorial for my sidebar, I found that it wasn't producing HTML5 compliant code since it was missing the appropriate <ul> and </ul> tags. I've updated the wp-includes/widgets.php file to produce code that's worked for me to pass validation and have a diff for patching, but just want to make sure that I've dotted all my i's and crossed all my t's and that I'm not overlooking anything.

[gfitzp]

Diff of the wp-includes/widgets.php file for patching

[greenshady]

The opening <ul> and closing </ul> should be in your template that's calling the sidebar. Each widget, by default, is a single list item (<li>).