Bug 154832 Wrong node is added to Report Parameters for cascading parameter in Palette view
Description: Wrong node is added to Report Parameters for cascading parameter in Palette view. Steps to reproduce: 1. New a report, add a cascading parameter 2. Switch to Script tab in Editor view, and then switch to Palette view 3. Expand Report Parameters node Expected result: A cascading parameter group is added to Report Parameters node Actual result: Expect a cascading parameter group is added to Report Parameters node, the children of the cascading parameter group are added as scalar parameters
UI/org.eclipse.birt.report.designer.ui.editors.schematic/src/org/eclipse/birt/report/designer/internal/ui/editors/script/JSEditor.java
* 
	 * @see org.eclipse.birt.report.designer.core.util.mediator.IColleague#performRequest(org.eclipse.birt.report.designer.core.util.mediator.request.ReportRequest)
	 */
	public void performRequest( ReportRequest request )
	{
		if ( ReportRequest.SELECTION.equals( request.getType( ) ) )
		{
			handleSelectionChange( request.getSelectionModelList( ) );
		}
		if ( ReportRequest.CREATE_ELEMENT.equals( request.getType( ) )
				&& request.getSelectionModelList( ).get( 0 ) instanceof ScriptDataSourceHandle )
		{
			handleSelectionChange( request.getSelectionModelList( ) );
		}
	}
	private void setComboViewerInput( Object model )
	{
		cmbExprListViewer.setInput( model );
		Object oldSelection = selectionMap.get( model );
		if ( oldSelection == null )
		{
			selectItemInComboExpList( new StructuredSelection( ) );
		}
		else
		{
			selectItemInComboExpList( (ISelection) oldSelection );
		}
		return;
	}
	private void setComboViewerInput( String message )