clean up clearGrid()

git-svn-id: http://svn.openlayers.org/trunk/openlayers@1150 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Grid.js

@@ -360,14 +360,11 @@ OpenLayers.Layer.Grid.prototype =
      */
     clearGrid:function() {
         if (this.grid) {
-            while(this.grid.length > 0) {
-                var row = this.grid[0];
-                while(row.length > 0) {
-                    var tile = row[0];
-                    tile.destroy();
-                    row.remove(tile);
+            for(var iRow=0; iRow < this.grid.length; iRow++) {
+                var row = this.grid[iRow];
+                for(var iCol=0; iCol < row.length; iCol++) {
+                    row[iCol].clear();
                 }
-                this.grid.remove(row);                   
             }
         }
     },