Revert "Debug info: Implement a cleaner version of r198461. For symmetry with"

This reverts commit 198699 so we can get a cleaner patch.
Revert "Debug info: Ensure that the last stop point in a function is still within"

This reverts commit r198461.
Re-applying r198699 after reverting r198461.
Debug info: Implement a cleaner version of r198461. For symmetry with
C and C++ don't emit an extra lexical scope for the compound statement
that is the body of an Objective-C method.