Fixing IndexOutOfBounds Exception in ActivityManager

Bypass the iteration to avoid the exception during
the execution of ensureActivityVisibleLocked() because
startSpecificActivityLocked() within the loop may delete
the elements from History stack.

Change-Id: I195da10a8e9161572bdb653ad3021998d4f2a939
CRs-Fixed: 651963
Merge "Fixing IndexOutOfBounds Exception in ActivityManager" into du44