More improvements to method invocation.

[bluelhf]

This PR makes three improvements to the looking glass:

1. It stores a constant pool reference of type InterfaceMethodRef for static interface methods, which fixes runtime errors.
2. It inverts the parameter type matching logic in findSmartMethod in order to find methods correctly.
3. It adds a null target guard clause to findSmartMethod, as the method may invoke itself with a null target when trying to find the method in the super-class of an interface (the super-class of an interface is always null).