Bug 156642 [Regression]Script of onPrepare is no effect
Details: Script of onPrepare is no effect Set any function on onPrepare, but it is no effect. For example: this.getStyle().color="red" Excepted: it is effect
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/RunTask.java
private ReportDocumentWriter writer;
	private IPageHandler pageHandler;
	private ReportDocumentBuilder documentBuilder;
	/**
	 * @param engine
	 *            the report engine
	 * @param runnable
	 *            the report runnable instance
	 */
	public RunTask( IReportEngine engine, IReportRunnable runnable )
	{
		super( engine, runnable );
		executionContext.setFactoryMode( true );
		executionContext.setPresentationMode( false );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.engine.api.IRunTask#setPageHandler(org.eclipse.birt.report.engine.api.IPageHandler)
	 */
	public void setPageHandler( IPageHandler callback )
	{
		this.pageHandler = callback;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.engine.api.IRunTask#run(java.lang.String)
	 */
	public void run( String reportDocName ) throws EngineException