Fix bug with CLEAR_TASK -- wouldn't clear the top activity.

Maybe this will also fix bug #5144065 as well.

I doubt I am so lucky, though.

Change-Id: I60bf595d3eff79353fdd94b0f2a089e81218bc30

Author: Dianne Hackborn

services/java/com/android/server/am/ActivityStack.java

@@ -2067,7 +2067,7 @@ private final ActivityRecord performClearTaskLocked(int taskId,
      * task starting at a specified index.
      */
     private final void performClearTaskAtIndexLocked(int taskId, int i) {
-        while (i < (mHistory.size()-1)) {
+        while (i < mHistory.size()) {
             ActivityRecord r = mHistory.get(i);
             if (r.task.taskId != taskId) {
                 // Whoops hit the end.