Better comments in ol.style.defaultStyleFunction

src/ol/style/style.js

@@ -169,8 +169,11 @@ ol.style.defaultStyleFunction = function(feature, resolution) {
     })
   ];
 
-  // now that we've run it the first time,
+  // Now that we've run it the first time, replace the function with
-  // replace the function with a constant version
+  // a constant version. We don't use an immediately-invoked function
+  // and a closure not to get an error at script evaluation time in
+  // browsers that do not support Canvas. ol.style.Circle indeed
+  // does canvas.getContext('2d') at construction time.
 
   /**
    * @param {ol.Feature} feature Feature.