Parser accepts invalid input

[sir-wabbit]

object Foo {
  val a = "");
}

[Blaisorblade]

Apparently acceptStatSepUnlessAtEnd will swallow a token without reporting it, but most tokens I can think get swallowed by expr() first. There obvious fix seems to work (see 8fd36a6), but has cascade effects (and the code seems a bit fishy anyway).

object Test {
  val a = ""); // error

  val b = 1;

  val c = b); // error
}