Bug 209119 Need WebViewer provide cancel function
Need WebViewer provide a cancel function, this will be used to cancel current report execution during designer preview.
viewer/org.eclipse.birt.report.viewer/src/org/eclipse/birt/report/viewer/utilities/WebViewer.java
}
	/**
	 * Stop web application
	 */
	private static void stopWebApp( )
	{
		try
		{
			WebappAccessor.stop( ViewerPlugin.WEBAPP_CONTEXT );
		}
		catch ( CoreException e )
		{
			
		}
	}
	/**
	 * Initiate the tomcat.
	 * 
	 */
	public static void startup( )
	{
		startWebApp( );
	}
	/**
	 * Initiate the tomcat.
	 * 
	 * @param browser
	 *            SWT browser
	 */
	public static void startup( Browser browser )