Remove Icon-specific code from Markers Layer, patch by meek,me,

r=euzuro.  (Closes #818)


git-svn-id: http://svn.openlayers.org/trunk/openlayers@9233 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Icon.js

@@ -78,6 +78,9 @@ OpenLayers.Icon = OpenLayers.Class({
      * references and memory leaks
      */
     destroy: function() {
+        // erase any drawn elements
+        this.erase();
+
         OpenLayers.Event.stopObservingElement(this.imageDiv.firstChild); 
         this.imageDiv.innerHTML = "";
         this.imageDiv = null;
@@ -143,6 +146,16 @@ OpenLayers.Icon = OpenLayers.Class({
         return this.imageDiv;
     }, 
 
+    /** 
+     * Method: erase
+     * Erase the underlying image element.
+     *
+     */
+    erase: function() {
+        if (this.imageDiv != null && this.imageDiv.parentNode != null) {
+            OpenLayers.Element.remove(this.imageDiv);
+        }
+    }, 
     
     /** 
      * Method: setOpacity