remove duplicate declaration of FootprintObj.js in DrawOp.js

Author: Cindy Wang

src/firefly/js/visualize/draw/DrawOp.js

@@ -8,7 +8,6 @@ import SelectBox from './SelectBox.js';
 import ShapeDataObj from './ShapeDataObj.js';
 import FootprintObj from './FootprintObj.js';
 import DirectionArrowDrawObj from './DirectionArrowDrawObj.js';
-import FootprintObj from './FootprintObj.js'
 import MarkerFootprintObj from './MarkerFootprintObj.js';
 
 export var drawTypes= {