/html/com_content/category/blog_item.php on line 23 template broken joomla 3 migration

/html/com_content/category/blog_item.php on line 23

This is the latest new from us. 

You can edit this description in the Content Category Manager. 

This will show the most recent article. You can easily change it to show more if you wish. 

The module on the left shows a list of older articles. 

Fatal error: Call to undefined method JHtml::core() in Z:\home\site\www\templates\testtemplate\html\com_content\category\blog_item.php on line 6 

How can you fix the bug? 

Be sure developers know how to fix it  
Meanwhile use the following workaround in blog_item.php: 

// Create a shortcut for params.

$params = &$this->item->params;

$images = json_decode($this->item->images);

$canEdit= $this->item->params->get('access-edit');

$publishdate = version_compare(JVERSION,'1.7.3','<') ? 'COM_CONTENT_PUBLISHED_DATE' : 'COM_CONTENT_PUBLISHED_DATE_ON';

JHtml::addIncludePath(JPATH_COMPONENT .'/helpers/html');

JHtml::_('behavior.tooltip');

// WM Anpassung an Joomla 3,0 Framework 12.1 

if (method_exists('JHtml','core')) 

JHtml::core(); 

else 

JHtmlBehavior::framework(); 

?>

It works for Joomla 2.5 AND Joomla 3.0