Validation (XHTML Error): "Title" Attribute for "Start" Time is Missing Quotation Marks

Event pages that specify a "Start" time are not valid XHTML, due to a validation error:

Error: an attribute value specification must be an attribute value literal unless SHORTTAG YES is specified

This is due to the "Start" time's "title" attribute not being surrounded by quotation marks in "event.theme". The "End" time's "title" attribute is surrounded by quotation marks and is not affected by this error.

Line 395, for the "End" time, has quotation marks surrounding the apostrophes for the "title" attribute:

    <div class="'. $node->type. '-end dtend" title="'. event_format_date($node->event['end'], 'custom', "Y-m-d\TH:i:s\Z") . '"><label>'. t('End: ') .'</label>'. $node->event['end_format'] .'</div></div>'."\n";

But line 392, for the "Start" time, does not:

    <div class="'. $node->type. '-start dtstart" title='. event_format_date($node->event['start'], 'custom', "Y-m-d\TH:i:s\Z") .'><label>'. t('Start: ') .'</label>'. $node->event['start_format'] .'</div></div>'."\n";

Adding quotation marks around the apostrophes for the "title" attribute in line 392 will fix this issue.