Bug 161501 [Smoke] Chart can not be previewed in Web Viewer & HTML
Chart can not be previewed in Web Viewer & HTML Steps to reproduce: 1. Create a chart. 2. Preveiw in Web Viewer/ HTML. Expected result: Chart can be previewed. Actual result: No chart is shown.
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/service/ReportEngineService.java
{
	private static ReportEngineService instance;
	/**
	 * Report engine instance.
	 */
	private IReportEngine engine = null;
	/**
	 * Static engine config instance.
	 */
	private EngineConfig config = null;
	/**
	 * Image directory for report images and charts.
	 */
	private String imageDirectory = null;
	/**
	 * URL accesses images.
	 */
	private String imageBaseUrl = null;
	/**
	 * Image handler instance.
	 */
	private HTMLServerImageHandler imageHandler = null;
	/**
	 * Web app context path.
	 */
	private String contextPath = null;
	/**
	 * Constructor.
	 * 
	 * @param servletConfig