The InlineKlassFixedBlock class has the following fields:
```
class InlineKlassFixedBlock {
  Array<SigEntry>** _extended_sig;
  Array<VMRegPair>** _return_regs;
  address* _pack_handler;
  address* _pack_handler_jobject;
  address* _unpack_handler;
  int* _null_reset_value_offset;
```

with associated functions that all look something like this:
  address adr_extended_sig() const {
    assert(_adr_inlineklass_fixed_block != nullptr, "Should have been initialized");
    return ((address)_adr_inlineklass_fixed_block) + in_bytes(byte_offset_of(InlineKlassFixedBlock, _extended_sig));
  }

Given the name of the function you would expect that it returned the address of the _extended_sig field, and the implementation seems to support this observation. So, the type above should be `Array<SigEntry>***`. However, callers of this function expects the type to be `Array<SigEntry>**` and casts it as such.

This all seems to work because we erase the type by casting to `address` and then it doesn't matter what types the InlineKlassFixedBlock fields have, as long as they are pointer fields.

I propose that we restructure the code to reduce the casting and fix the type confusion.