Pzhang/security classes

Fixed a vm bug, it failed to execute the following class (NullPointerException is thrown):

```java
package java.lang;

import gnu.testlet.Testlet;
import gnu.testlet.TestHarness;

public class TestLJ implements Testlet {
    private TestLJ() {
        method(null);
    }
    private void method(long[] param2) {
    }
    public void test(TestHarness th) {
       // If this method is invoked, it means test passed.
       th.check(true);
    }
}
```
because the number of the IN slots of |method| is counted as 3 which should be 2.