Failing to compile functions with `{` on the start of next line

In scalac it is possible to compile the following:
```scala
def foo(x: Int) 
{
  x
}
```

In dotty with `-language:Scala2` the following error is emitted.
```
    |    x
    |    ^
    |    not found: x
```

This kind of code can be found in `scala/io/Source.scala` and this is why it is not whitelisted.
