Nim/tests/overload/tvartypeclass.nim

# issue #13302

proc foo(x: object): int = x.i*2
proc foo(x: var object) = x.i*=2
type Foo = object
  i: int
let x = Foo(i: 3)
var y = Foo(i: 4)
doAssert foo(x) == 6
foo(y)
doAssert y.i == 8