Bug 121166 in the second time use of scripted data set, the result is null
1: Create a scripted data source 2: Create a scripted data set 3: Drag this data set to report design to create a table 4: Do step 4 again to create the second table 5: Preview report, the first table has result but the second table is null Expected: 5: the first table and the second table have the same result
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/script/internal/DtEScriptExecutor.java
{
		if ( runner == null )
		{
			String scopeName = type + "[" + name + "]";
			runner = new JSMethodRunner( scope, scopeName );
		}
		return runner;
	}
	protected JSScriptStatus handleJS( Scriptable scope, String type,
			String name, String method, String script )
	{
		if ( script == null || type == null || name == null || method == null )
			return JSScriptStatus.NO_RUN;
		if ( !( DATA_SET.equals( type ) || DATA_SOURCE.equals( type ) ) )
			return JSScriptStatus.NO_RUN;
		Object result = null;
		try
		{
			JSMethodRunner jsr = getRunner( scope, type, name );
			result = jsr.runScript( method, script );
		} catch ( Exception e )
		{
			e.printStackTrace( );
		}
		return new JSScriptStatus( true, result );
	}
	protected abstract JSScriptStatus handleJS( Scriptable scope, String name,
			String method, String script );
}