Fix debugging for IronPython (PY-20959)

Remove duplication and fix generator exception

python/helpers/pydev/_pydevd_bundle/pydevd_constants.py

@@ -28,10 +28,7 @@ try:
             try:
                 return sys._getframe()
             except ValueError:
-                if IS_IRONPYTHON:
-                    pass
-                else:
-                    raise
+                pass
 except AttributeError:
     def get_frame():
         raise AssertionError('sys._getframe not available (possible causes: enable -X:Frames on IronPython?)')

python/helpers/pydev/_pydevd_bundle/pydevd_tracing.py

@@ -79,6 +79,8 @@ def _do_not_trace_ctx():
     current_thread.pydev_do_not_trace = True
     try:
         yield
+    except:
+        pass
     finally:
         current_thread.pydev_do_not_trace = do_not_trace_before