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
* style of this element or an ancestor element; it is not considered set if
	 * it is inherited from a shared style.</li>
	 * </ul>
	 * 
	 * @param module
	 *            the module
	 * @param prop
	 *            definition of the property
	 * @return the value of the property according to the rules explained above
	 */
	public Object getFactoryProperty( Module module, ElementPropertyDefn prop )
	{
		
		
		assert !prop.isStyleProperty( );
		return getProperty( module, prop );
	}
	/**
	 * Creates the Factory data structures for specialized property access. This
	 * method uses specialized property resolution rules:
	 * <p>
	 * <ul>
	 * <li>A property value is either a style property or a non-style property.
	 * </li>
	 * <li>A non-style property is set if this element, or any of its ancestor
	 * elements, provide a value. It is also considered set if the system
	 * provides a default value.</li>
	 * <li>A property value is considered set only if it is set in the private
	 * style of this element or an ancestor element; it is not considered set if
	 * it is inherited from a shared style.</li>