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.enterScope( );
	}
	/**
	 * create a new scope, use the object to create the curren scope.
	 * 
	 * @param object
	 *            the "this" object in the new scope
	 */
	public void newScope( Object object )
	{
		Object jsObject = scriptContext.javaToJs( object );
		if ( jsObject instanceof Scriptable )
		{
			scriptContext.enterScope( (Scriptable) jsObject );
		}
		else
		{
			scriptContext.enterScope( );
		}
	}
	/**
	 * exits a variable scope.
	 */
	public void exitScope( )
	{
		scriptContext.exitScope( );
	}
	/**
	 * register beans in the execution context