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
{
		DesignElement element = this;
		while ( element.getContainer( ) != null )
			element = element.getContainer( );
		if ( element instanceof Module == false )
			return null;
		return (Module) element;
	}
	/**
	 * Implements to broadcast an event to all listeners of this design element.
	 * Implementations of sendEvent( ) call this to do the actual work of
	 * broadcasting.
	 * <p>
	 * Part of: Notification system.
	 * 
	 * @param ev
	 *            the event to send
	 */
	public final void broadcast( NotificationEvent ev )
	{
		if ( this instanceof Module || getContainer( ) != null )
			broadcast( ev, getRoot( ) );
	}
	/**
	 * Implements to broadcast an event to all listeners of this design element
	 * on a design tree. Note subclasses should override this method to change
	 * the behavior of broadcast method.
	 * 
	 * Part of: Notification system.
	 *