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/core/DesignElement.java
* 
	 * @return The list of user properties.
	 */
	public List getLocalUserProperties( )
	{
		if ( userProperties == null )
			return Collections.EMPTY_LIST;
		return new ArrayList( userProperties.values( ) );
	}
	/**
	 * Checks if this element derives from the given element. The check is true
	 * if this element derives from the target, or if the target is an ancestor
	 * of this element.
	 * 
	 * @param element
	 *            The potential ancestor.
	 * @return True if the given element is an ancestor of this element, false
	 *         otherwise.
	 */
	public boolean isKindOf( DesignElement element )
	{
		DesignElement e = this;
		while ( e != null )
		{
			if ( e == element )
				return true;
			e = e.getExtendsElement( );
		}
		return false;
	}