Follow up I1f0c56651eaa59f0ce90cdb08c71e89a96c48dd4

Beside addressing the comments on this change, this adds a check that
the token in end( is correct and prints a message if not. This is useful
when creating new dumping methods.

Test: adb shell dumpsys print
Change-Id: Ic2e6152cbd82f98d9d305a15edffc69c55fd1fd3