Bug 199834 Enable access to IContent object in IReportItemPresentation layer
In IReportItemPresentation layer, the extended item may want to access properties from current IContent object, for example, bookmark, content style. So we need expose the content object in this layer.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/presentation/LocalizedContentVisitor.java
case IReportItemPresentation.OUTPUT_AS_CUSTOM :
				IDataContent dataObj = reportContent.createDataContent( content );
				dataObj.setValue( output );
				processData( dataObj );
				return dataObj;
			case IReportItemPresentation.OUTPUT_AS_HTML_TEXT :
				content.setRawType( IForeignContent.HTML_TYPE );
				content.setRawValue( output.toString( ) );
				return content;
			case IReportItemPresentation.OUTPUT_AS_TEXT :
				ITextContent textObj = reportContent.createTextContent( );
				textObj.setText( output.toString( ) );
				return textObj;
				
			default :
				assert false;
				logger.log( Level.WARNING, "unsupported output format:{0}", 
						new Integer( type ) );
		}
		return content;
	}
	/**
	 * read the content of input stream.
	 * 
	 * @param in
	 *            input content
	 * @return content in the stream.
	 */
	static protected byte[] readContent( InputStream in )
	{