Matcher should always work with the whole expression, including Convert

Without this change, the following code doesn't work correctly,
because the passed in long is compared against int.

interface IFoo
{
    string M(long l);
}

var mock = new Mock<IFoo>(MockBehavior.Strict);
mock.Setup(x => x.M(int.Parse("2"))).Returns("OK");
var result = mock.Object.M(2L);