Using proper key for removing from map.

Window object was improperly used as a key for removing record from
map. This was silenly ignored, because remove() method accepts Object.
However, the ID should be used there which is type of String, i.e.
the same ID which was used for lookup.

Change-Id: I81fc2f90926a34414bf9042ddf4a2edff4c1fda1

core/java/android/app/LocalActivityManager.java

@@ -380,7 +380,7 @@ public class LocalActivityManager {
         if (r != null) {
             win = performDestroy(r, finish);
             if (finish) {
-                mActivities.remove(r);
+                mActivities.remove(id);
             }
         }
         return win;