Bug 121498 When datasource/dataset deleted, the datasource/dataset property binding element haven't been deleted
When deleted the datasource/dataset, the datasource/dataset property binding element haven't been deleted. Expected result: This operation must be a transaction.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DesignElementHandle.java
/**
	 * Sets the group expression.
	 * 
	 * @param expr
	 *            the expression to set
	 * @throws SemanticException
	 *             If the expression is invalid.
	 * 
	 * @see #getEventHandlerClass()
	 */
	public void setEventHandlerClass( String expr ) throws SemanticException
	{
		setProperty( GroupElement.EVENT_HANDLER_CLASS_PROP, expr );
	}
	/**
	 * Creates a template element handle and transforms the current element
	 * handle to the created template element.
	 * 
	 * @param name
	 *            the name of created template element handle
	 * @return the template element handle
	 * @throws SemanticException
	 *             if the current element can not be transformed to a template
	 *             element, current module is not a report design or some
	 *             containing contexts don't match
	 */
	public TemplateElementHandle createTemplateElement( String name )
			throws SemanticException
	{
		if ( getRoot( ) == null )