Fix up instanceof exception checks in PHP code

[jng]

There are still sections of the PHP codebase doing instanceof checks against exception classes that no longer exist.

These should be migrated over to be tests by exception code

[jng]

In 10059:

Update final cases of instanceof exception checks in PHP code

Fixes #2876

[jng]

In 10060:

Merged revision(s) 10059 from branches/4.0/MgDev:
Update final cases of instanceof exception checks in PHP code

Fixes #2876
........