Revert "Revert "ART: Ignore try blocks with no throwing instructions""

The original CL broke libcore tests because monitor-exit instructions
did not have any side-effects and got removed by DCE once not labelled
throwing any more.

This reverts commit efe374d7c25c1d48945a9198d96469de99e0c1bd.

Change-Id: I624c0f91676d9baaada6f33be9d7091f68d57535
5 files changed