the grid layer needs to clear its tile loading timeout when it's removed from the map, or moveGriddedTiles can be called with this.map set to null, r=crschmidt (closes #3110)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@11482 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Grid.js

@@ -131,6 +131,20 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
         );
     },
 
+    /**
+     * Method: removeMap
+     * Called when the layer is removed from the map.
+     *
+     * Parameters:
+     * map - {<OpenLayers.Map>} The map.
+     */
+    removeMap: function(map) {
+        if(this.timerId != null) {
+            window.clearTimeout(this.timerId);
+            this.timerId = null;
+        }
+    },
+
     /**
      * APIMethod: destroy
      * Deconstruct the layer and clear the grid.