`Contains` lambda not compiling when coupled with `IsNotNull`

[robertcoltheart]

More regressions / defects in assertions.

See test case below:

[Test]
public async Task Test()
{
    var dictionary = new Dictionary<string, string>();

    await Assert.That(dictionary).Contains(x => x.Key == "key"); // Compiles
    await Assert.That(dictionary).IsNotNull().And.Contains(x => x.Key == "key"); // Does not compile
}