Fix an issue with the positions of InstanceNames that used the original position_modifier.

jedi/evaluate/representation.py

@@ -260,7 +260,7 @@ class LazyInstanceDict(object):
 
 class InstanceName(pr.Name):
     def __init__(self, origin_name, parent):
-        super(InstanceName, self).__init__(origin_name.position_modifier,
+        super(InstanceName, self).__init__(pr.zero_position_modifier,
                                            origin_name.value,
                                            origin_name.start_pos)
         self._origin_name = origin_name

jedi/parser/tree.py

@@ -158,9 +158,7 @@ class Leaf(Base):
 
     @start_pos.setter
     def start_pos(self, value):
-        # TODO I think this is wrong, because the position_modifier.line needs
-        # to be looked at as well. Probably it needs to be substracted.
-        self._start_pos = value
+        self._start_pos = value[0] - self.position_modifier.line, value[1]
 
     @property
     def end_pos(self):