Bug 124620 Referenced Parameter icon should be invalid if the parameter in library is deleted
Description: Referenced parameter icon should be invalid if the source parameter in library is deleted. Steps to reproduce: 1.Create a library. Insert a report scalar parameter. 2.Create a report, use the above library. In the library explorer, pull the parameter to the data explorer view of report. 3.Open the library file, delete the parameter. Then reopen the report design file, the icon of parameter seems nothing happened. But if those operations happened in dataset, the icon of dataset in the report will be invalid. It is acceptable. Expected Result: The icon of referenced parameter should be invalid.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DesignElementHandle.java
/**
	 * Adds a report item to the given slot at the given position. The item must
	 * be newly created and not yet added to the design.
	 * 
	 * @param child
	 *            handle to the newly created element
	 * @param slotId
	 *            slot id in which the child item will be added.
	 * @param pos
	 *            position in the slot that the child item will be added.
	 * @throws ContentException
	 *             if the element is not allowed in the slot
	 * @throws NameException
	 *             if the element has a duplicate or illegal name
	 * 
	 */
	public void addElement( DesignElementHandle child, int slotId, int pos )
			throws ContentException, NameException
	{
		SlotHandle slotHandle = getSlot( slotId );
		if ( slotHandle != null )
			slotHandle.add( child, pos );
	}
	/**
	 * Adds a report item to the end of the given slot. The item must be newly
	 * created and not yet added to the design.
	 * 
	 * @param child
	 *            handle to the newly created element
	 * @param slotId