Tests with legacy ExpectedException attributes always pass

[Charlie Poole]

Actual behaviour:

The following test when compiled against the NUnit 2.4 'nunit.framework'
passes when executed with NUnit 2.5:

[Test, ExpectedException("UnknownException")]
public void ShouldFail()
{
throw new NullReferenceException();
}

Expected behaviour:

Test should fail.

This only happens when tests have been compiled against 'nunit.framework'
2.4 or earlier.

I'm guessing it will have something to do with the extra properties in the
2.5 version of this attribute.

[From SF Bug #2837070]

[Charlie Poole (charlie.poole)]

Needs to be confirmed first.