Wrong highlighted line for function parameters

[laike9m]

Example: https://github.com/laike9m/Cyberbrain/blob/master/examples/twelve_days/twelve.py

day should be on line 14, but line 47 is highlighted.

[laike9m]

Since dealing with global and enclosing vars are very hard, for now we can ignore them. So the fix would be:

• If initial value comes from an argument, use the correct lineno
• Otherwise use a special value like -1