Bug 167511 [Block]NPE when using customized IStyleProcessor with Chart Generator and no Chart will be rendered
Use a customized IStyleProcessor with Generator.build() and the chart will not be rendered in UI.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/factory/Generator.java
*            Chart design model
	 * @param externalContext
	 *            External Context
	 * @param locale
	 *            Locale
	 * @return a runtime context used by build( )
	 * 
	 * @throws ChartException
	 * 
	 * @since 2.1
	 */
	public RunTimeContext prepare( Chart model,
			IExternalContext externalContext, IScriptClassLoader iscl,
			ULocale locale ) throws ChartException
	{
		RunTimeContext rtc = new RunTimeContext( );
		rtc.setScriptClassLoader( iscl );
		
		final Chart cmRunTime = (Chart) EcoreUtil.copy( model );
		rtc.setULocale( locale != null ? locale : ULocale.getDefault( ) );
		ChartScriptContext csc = new ChartScriptContext( );
		csc.setChartInstance( cmRunTime );
		csc.setExternalContext( externalContext );
		csc.setULocale( rtc.getULocale( ) );
		csc.setLogger( logger );
		rtc.setScriptContext( csc );
		ScriptHandler sh = new ScriptHandler( );
		rtc.setScriptHandler( sh );
		sh.setScriptClassLoader( iscl );
		sh.setScriptContext( csc );