is_object_aligned only works correctly for sizes measured in words.

When a pointer is passed into:
inline bool is_object_aligned(intptr_t addr) {
  return addr == align_object_size(addr);
}

inline intptr_t align_object_size(intptr_t size) {
  return align_size_up(size, MinObjAlignment);
}

the pointer is incorrectly interpreted as a word size and the alignment is checked against MinObjectAligment instead of MinObjectAlignmentInBytes.

This was found while working on JDK-8178489.