Bug 165278 this.getDisplayContent()="" in script of text will destroy preview[0801]
Description: this.getDisplayContent()="" in script of text will destroy preview Build number:2.1.2.v20061120 and 2.2.0.v20061117 Steps to reproduce: 1. Insert a text item, select it and switch to script editor 2. Input this.getDisplayContent()="" and preview Expected result: Error message about the incorrect script. Actual result: In 2.1.2, I saw HTTP Status 500 - type Exception report message description The server encountered an internal error () that prevented it from fulfilling this request. In 2.2.0, I saw error dialog with java.lang.ClassCastException.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/executor/ExecutionContext.java
* @see evaluate(String,String,int)
	 */
	public Object evaluate( String source )
	{
		return evaluate( source, "<inline>", 1 );
	}
	/**
	 * Evaluate a BIRT expression
	 * 
	 * @param expr
	 *            the expression to be evaluated
	 * @param name
	 *            the file name
	 * @param lineNo
	 *            the line number
	 * 
	 * @return the result if no error exists, otherwise null.
	 */
	public Object evaluate( String expr, String name, int lineNo )
	{
		if ( expr != null )
		{
			try
			{
				return scriptContext.eval( expr, name, lineNo );
			}
			catch ( Exception e )
			{