Test for crashing Ruby when object doesn't have :=== method in case

This commit tests recently [fixed bug](http://svn.ruby-lang.org/cgi-bin/viewvc.cgi/trunk/vm_insnhelper.c?r1=43913&r2=43912&pathrev=43913). The problem is consists of the following: when we have object which doesn't have defined `:===` method Ruby crashes in case statement. `BasicObject` doesn't have this method and the bug is reproduced on this object:

```ruby
case 1
when BasicObject.new
end
```

And we have crash.