ECJ doesn't report expected error about domination

Here's the testcase:

```
public class X {
	public int foo(Character c) {
		int result = 0;
		switch (c) {
			case Character c1 -> {
				result = c1;
				break;
			}
			case 0 -> {  // Same goes for case (int) 0
				result = 0;
				break;
			}
		}
		return result;
	}
}
```

Javac reports this -` error: this case label is dominated by a preceding case label` but we allow this.