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
scriptContext = new ScriptContext( );
		}
		initailizeScriptContext( scriptContext.getContext( ), scriptContext
				.getRootScope( ) );
		
		
		scriptContext.registerBean( "report", new ReportObject( ) );
		scriptContext
				.registerBean(
						"params", new ScriptableParameters( params, scriptContext.getScope( ) ) ); 
		scriptContext.registerBean( "config", configs ); 
		scriptContext.registerBean( "currentPage", new Long( pageNumber ) );
		scriptContext.registerBean( "totalPage", new Long( totalPage ) );
		scriptContext.registerBean( "_jsContext", this );
		scriptContext
				.eval( "function registerGlobal( name, value) { _jsContext.registerGlobalBean(name, value); }" );
		scriptContext
				.eval( "function unregisterGlobal(name) { _jsContext.unregisterGlobalBean(name); }" );
		
		applicationClassLoader = new ApplicationClassLoader( this );
		scriptContext.getContext( ).setApplicationClassLoader(
				applicationClassLoader );
		
	}
	protected void initailizeScriptContext( Context cx, Scriptable scope )
	{
		scriptContext.getContext( ).setWrapFactory( new WrapFactory( ) {
			protected IJavascriptWrapper coreWrapper = new CoreJavaScriptWrapper( );
			/**
			 * wrapper an java object to javascript object.