Cleanup: Get rid of calls to builtin_{push,pop}_catch_scope in the IR

Cleanup: Get rid of calls to builtin_{push,pop}_catch_scope in the IR

These calls aren't needed anymore and can easily be done on the run-time level
instead right before and after calling the catch block.

Change-Id: I445361688782d12269764578e83ebb21ae184190
Reviewed-by: Lars Knoll <lars.knoll@digia.com>