RFR: 8158045: Improve large object handling during evacuation

[Albert Yang]

Hi,

Sorry, I accidentally pressed "send" before finishing my review ...

```
  499     if (klass->is_array_klass()) {
  500       if (klass->is_typeArray_klass()) {
  501         // Nothing needs to be done for typeArrays.  Body doesn't contain
  502         // any oops to scan, and the type in the klass will already be handled
  503         // by processing the built-in module.
  504         return obj;
  505       } else if (klass->is_objArray_klass()) {
  506         // Do special handling for objArray.
  507         return start_partial_objArray(dest_attr, old, obj);
  508       }
  509       // Not a special array, so fall through to generic handling.
  510     }
```

I thought an array can only be typeArray or objArray. What is the third case?

Since each if branch contains a `return`, putting each if-condition in a separate line 
could make each case more distinguishable.

```
if (klass->is_typeArray_klass()) {
   return ...;
}

if (klass->is_objArray_klass()) {
   return ...;
}
```

-- 
/Albert