Bitmap.bitmapDataを後から突っ込むとsmoothingがfalseになる

/**
 * Copyright undo ( http://wonderfl.net/user/undo )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/hk9h
 */

package {
	import flash.text.TextField;
	import flash.text.TextFieldAutoSize;
    import flash.display.*;
    
    public class FlashTest extends Sprite {
        public function FlashTest() {
        		var tf:TextField = new TextField();
        		tf.autoSize = TextFieldAutoSize.LEFT;
        		addChild(tf);
        		
        		
            var bmp:Bitmap = new Bitmap();
			bmp.smoothing = true;
			tf.appendText("普通にsmoothing = trueした時 --> " + bmp.smoothing + "\n");

			var bmpdata:BitmapData = new BitmapData(10,10);
			bmp.bitmapData = bmpdata;
			tf.appendText("bitmapDataを後から突っ込むと --> " + bmp.smoothing + "\n");
        }
    }
}