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
/**
	 * Slot in the container in which this element resides.
	 */
	protected int containerSlotID = NO_SLOT;
	/**
	 * Listeners are the objects that want to be notified of events. Contents
	 * are of type Listener. Created only when needed.
	 */
	protected ArrayList listeners = null;
	/**
	 * Values for non-intrinsic property values. The contents are of type
	 * Object.
	 */
	protected Map propValues = new HashMap( );
	/**
	 * Definitions for user-defined properties. Contents are of type
	 * UserPropertyDefn.
	 */
	protected HashMap userProperties = null;
	/**
	 * Support for inheritance. Represents the resolved or unresolved element
	 * that this element extends.
	 */
	protected ElementRefValue extendsRef = null;
	/**
	 * Inverse of the extends relationship: parent-->derived. Very few elements
	 * are extended, so we create this list only when needed.
	 */
	protected ArrayList derived = null;
	/**