bad tree position for valdef

in this code
```scala
class ValVsDef {
  val x = 1
  val y = 1
  val lol = x + y
  def rofl = x + lol
}
```
the valdef for lol val position points to + symbol
for other vals and defs it correctly points to the name
an example can be found at https://github.com/OlegYch/browse/blob/master/test/ValVsDef.scala 
execute it with sbt 'test/testOnly ValVsDef.scala'