Contribution of PowerPC port (continuation of 422063005) - serialize.cc cleanup

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index 44262e42b162b58974cf7b2092ea141047856d2a..dc5e8e315569e19afad78ffa35c911231a3f6357 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -2875,12 +2875,14 @@ class PointersUpdatingVisitor : public ObjectVisitor {
 
 // TODO(ishell): remove, once crbug/454297 is caught.
 #if V8_TARGET_ARCH_64_BIT
+#ifndef V8_OS_AIX  // no point checking on AIX as full 64 range is supported
     const uintptr_t kBoundary = V8_UINT64_C(1) << 48;
     STATIC_ASSERT(kBoundary > 0);
     if (reinterpret_cast<uintptr_t>(heap_obj->address()) >= kBoundary) {
       CheckLayoutDescriptorAndDie(heap, slot);
     }
 #endif
+#endif
     MapWord map_word = heap_obj->map_word();
     if (map_word.IsForwardingAddress()) {
       DCHECK(heap->InFromSpace(heap_obj) ||