Merge pull request #1815 from Intermedix/lazy-style-function

Lazily create styles returned by ol.defaultFeatureStyleFunction.

src/ol/feature.js

@@ -221,7 +221,7 @@ ol.feature.FeatureStyleFunction;
  * @this {ol.Feature}
  * @todo stability experimental
  */
-ol.feature.defaultFeatureStyleFunction = (function() {
+ol.feature.defaultFeatureStyleFunction = function(resolution) {
   var fill = new ol.style.Fill({
     color: 'rgba(255,255,255,0.4)'
   });
@@ -240,10 +240,17 @@ ol.feature.defaultFeatureStyleFunction = (function() {
       stroke: stroke
     })
   ];
-  return function(resolution) {
+
-    return styles;
+  // now that we've run it the first time,
-  };
+  // replace the function with a constant version
-})();
+  ol.feature.defaultFeatureStyleFunction =
+      /** @type {function(this:ol.Feature):Array.<ol.style.Style>} */(
+      function(resolution) {
+        return styles;
+      });
+
+  return styles;
+};
 
 
 /**