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/elements/ExtendedItem.java
* @see org.eclipse.birt.report.model.core.DesignElement#getLocalProperty(Module,
	 *      org.eclipse.birt.report.model.metadata.ElementPropertyDefn)
	 */
	public Object getLocalProperty( Module module, ElementPropertyDefn prop )
	{
		assert prop != null;
		if ( !prop.isExtended( ) )
			return super.getLocalProperty( module, prop );
		return provider.getExtensionProperty( prop.getName( ) );
	}
	/**
	 * Sets the value of a property. The value must have already been validated,
	 * and must be of the correct type for the property. The property must be
	 * valid for this object. The property can be a system, user-defined
	 * property and a property from the extended element of this item. The value
	 * is set locally. If the value is null, then the property is "unset."
	 * 
	 * @see org.eclipse.birt.report.model.core.DesignElement#setProperty(org.eclipse.birt.report.model.metadata.ElementPropertyDefn,
	 *      java.lang.Object)
	 */
	public void setProperty( ElementPropertyDefn prop, Object value )
	{
		assert prop != null;
		if ( !prop.isExtended( ) )
			super.setProperty( prop, value );
		else
			provider.setExtensionProperty( prop, value );
	}
	/**
	 * Gets the property data for either a system-defined, user-defined property