Back out the fix for Bug #18656 as PHP (5.3.7 and 5.4) no longer emits a warning when is_a is passed an appropriate string.
Back out the fix for Bug #18656 as PHP (5.3.7 and 5.4) no longer emits a warning when is_a is passed an appropriate string.

git-svn-id: 4b064e69dc630d28214c1e1442d27300cccf8e9a@313340 c90b9560-bf6c-de11-be94-00142212c4b1

DQNEO/PEAR_Exception