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/extension/PeerExtensibilityProvider.java
* 
	 * @param propName
	 *            name of the property
	 * @return the element property definition with the given name
	 */
	public IPropertyDefn getPropertyDefn( String propName )
	{
		IPropertyDefn propDefn = super.getPropertyDefn( propName );
		if ( propDefn == null )
		{
			PeerExtensionElementDefn extDefn = (PeerExtensionElementDefn) getExtDefn( );
			IPropertyDefinition[] extProps = getExtensionModelPropertyDefns( );
			if ( extProps != null )
			{
				for ( int i = 0; i < extProps.length; i++ )
				{
					if ( propName.equalsIgnoreCase( extProps[i].getName( ) ) )
					{
						return new ExtensionModelPropertyDefn( extProps[i],
								extDefn.getReportItemFactory( ).getMessages( ) );
					}
				}
			}
		}
		return propDefn;
	}
	/**
	 * Gets all the extension model properties defined by
	 * <code>IReportItem</code>.
	 *