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
if ( IForeignContent.EXTERNAL_TYPE.equals( rawFormat ) )
		{
			return processExtendedContent( foreignContent );
		}
		
		if ( IForeignContent.IMAGE_TYPE.equals( rawFormat ) )
		{
			if ( rawValue instanceof IImageContent )
			{
				IImageContent image = (IImageContent) rawValue;
				processImage( image );
				return image;
			}
			if ( rawValue instanceof byte[] )
			{
				IImageContent imageContent = reportContent
						.createImageContent( foreignContent );
				imageContent.setImageSource( IImageContent.IMAGE_EXPRESSION );
				imageContent.setData( (byte[]) rawValue );
				processImage( imageContent );
				return imageContent;
			}
		}
		
		if ( IForeignContent.TEXT_TYPE.equals( rawFormat ) )
		{
			handleOnRender( foreignContent );
			ITextContent textContent = reportContent
					.createDataContent( foreignContent );