Revert "Fix php warning"

This reverts commit 9588bfb2f0209c6eedbe32bbe41d4b2c58d0296c.
Revert "Fix php warning"

This reverts commit 3a7ee4c169ea511ad498b1f874f4703490db2a6d.
Revert "Fix broken test."

This reverts commit 5059b40e459f3a92f57f218af74b4477fc7ec06f.
Revert "Update String_Engine.php"

This reverts commit c39a5eea3688b9538200174cd6cb89e5cf4006a8.