Set opacity on layer div, not on tiles and markers. r=fredj (closes #3431)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@12185 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Markers.js

@@ -60,22 +60,6 @@ OpenLayers.Layer.Markers = OpenLayers.Class(OpenLayers.Layer, {
         OpenLayers.Layer.prototype.destroy.apply(this, arguments);
     },
 
-    /**
-     * APIMethod: setOpacity
-     * Sets the opacity for all the markers.
-     * 
-     * Parameter:
-     * opacity - {Float}
-     */
-    setOpacity: function(opacity) {
-        if (opacity != this.opacity) {
-            this.opacity = opacity;
-            for (var i=0, len=this.markers.length; i<len; i++) {
-                this.markers[i].setOpacity(this.opacity);
-            }
-        }
-    },
-
     /** 
      * Method: moveTo
      *