Create 'type' annotation for 'const' variables

From https://developers.google.com/closure/compiler/docs/js-for-compiler:
  "The type declaration and additional comment are optional. If you
  provide a type declaration, put the declaration on a separate line."

src/ol/interaction/dragzoominteraction.js

@@ -20,7 +20,8 @@ ol.SHIFT_DRAG_ZOOM_HYSTERESIS_PIXELS = 8;
 
 
 /**
- * @const {number}
+ * @const
+ * @type {number}
  */
 ol.SHIFT_DRAG_ZOOM_HYSTERESIS_PIXELS_SQUARED =
     ol.SHIFT_DRAG_ZOOM_HYSTERESIS_PIXELS *