reverting r12228 and r12185 (closes #3431)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@12231 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/WFS.js

@@ -590,5 +590,21 @@ OpenLayers.Layer.WFS = OpenLayers.Class(
         return extent;
     },
     
+    /** 
+     * APIMethod: setOpacity 
+     * Call the setOpacity method of the appropriate parent class to set the
+     *     opacity.  
+     * 
+     * Parameter: 
+     * opacity - {Float} 
+     */
+    setOpacity: function (opacity) {
+        if (this.vectorMode) {
+            OpenLayers.Layer.Vector.prototype.setOpacity.apply(this, [opacity]);
+        } else {
+            OpenLayers.Layer.Markers.prototype.setOpacity.apply(this, [opacity]);
+        }    
+    },
+
     CLASS_NAME: "OpenLayers.Layer.WFS"
 });