Bug 213680 [2.2.2]Chart script can not be cleaned completely.
Description: Reset script or delete all script does not work. build version: v20071221-0630 steps to reproduce: 1. New a report. 2. New a chart. 3. Enter some script for the chart and save the report. 4. Click the reset scirpt button or delete all script. 5. Save the report and switch to layout,then switch back to script page. Expected result: Script are cleaned. Actual result: Script are not cleaned. Note: If you delete part of the script, it works.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/PropertyCommand.java
* Private method to validate the value of a property.
	 * 
	 * @param prop
	 *            definition of the property to validate
	 * @param value
	 *            the value to validate
	 * @return the value to store for the property
	 * @throws PropertyValueException
	 *             if the value is not valid
	 */
	private Object validateValue( ElementPropertyDefn prop, Object value )
			throws SemanticException
	{
		
		if ( value == null )
			return null;
		Object input = value;
		
		if ( value instanceof DesignElementHandle )
		{
			DesignElementHandle elementHandle = (DesignElementHandle) value;
			Module root = elementHandle.getModule( );
			input = ReferenceValueUtil.needTheNamespacePrefix( elementHandle
					.getElement( ), root, module );
		}
		Object retValue = null;
		try
		{
			retValue = prop.validateValue( module, input );
		}