If the pan tween is playing when the map is destroyed, stop the tween. r=pspencer (closes #2156)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@9526 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Map.js

@@ -632,6 +632,11 @@ OpenLayers.Map = OpenLayers.Class({
         if (!this.unloadDestroy) {
             return false;
         }
+        
+        // make sure panning doesn't continue after destruction
+        if(this.panTween && this.panTween.playing) {
+            this.panTween.stop();
+        }
 
         // map has been destroyed. dont do it again!
         OpenLayers.Event.stopObserving(window, 'unload', this.unloadDestroy);