Do not copy by reference size/bounds/position in making a new tile. All tests pass ie6/ff (Closes #1026).

git-svn-id: http://svn.openlayers.org/trunk/openlayers@4579 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Tile.js

@@ -93,10 +93,10 @@ OpenLayers.Tile = OpenLayers.Class({
      */   
     initialize: function(layer, position, bounds, url, size) {
         this.layer = layer;
-        this.position = position;
-        this.bounds = bounds;
+        this.position = position.clone();
+        this.bounds = bounds.clone();
         this.url = url;
-        this.size = size;
+        this.size = size.clone();
 
         //give the tile a unique id based on its BBOX.
         this.id = OpenLayers.Util.createUniqueID("Tile_");