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
*            The potential container.
	 * @return True if this element is contained in the container either
	 *         directly or indirectly. False if this element is not contained.
	 *         If the given element is this element itself, return true.
	 */
	public boolean isContentOf( DesignElement element )
	{
		DesignElement e = this;
		while ( e != null )
		{
			if ( e == element )
				return true;
			e = e.container;
		}
		return false;
	}
	/**
	 * Returns the value of a property as a number (BigDecimal).
	 * 
	 * @param module
	 *            the module
	 * @param propName
	 *            the name of the property to get
	 * @return the property as a BigDecimal, or null if the value is not set or
	 *         cannot convert to a number
	 */
	public BigDecimal getNumberProperty( Module module, String propName )
	{
		Object value = getProperty( module, propName );
		if ( value == null )