Simplify default export

This removes unnecessary variable declarations where the default object is an object.

src/ol/style/TextPlacement.js

@@ -1,6 +1,7 @@
 /**
  * @module ol/style/TextPlacement
  */
+
 /**
  * Text placement. One of `'point'`, `'line'`. Default is `'point'`. Note that
  * `'line'` requires the underlying geometry to be a {@link ol.geom.LineString},
@@ -8,9 +9,7 @@
  * {@link ol.geom.MultiPolygon}.
  * @enum {string}
  */
-var _ol_style_TextPlacement_ = {
+export default {
   POINT: 'point',
   LINE: 'line'
 };
-
-export default _ol_style_TextPlacement_;