Fix another may not be init compile error on AIX

src/heap/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 2398 matching lines @@
         Max(kMinimumOldGenerationAllocationLimit,
             static_cast<intptr_t>(
                 static_cast<double>(old_generation_allocation_limit_) *
                 (tracer()->AverageSurvivalRatio() / 100)));
   }
 }
 
 
 AllocationResult Heap::AllocatePartialMap(InstanceType instance_type,
                                           int instance_size) {
-  Object* result;
+  Object* result = nullptr;
   AllocationResult allocation = AllocateRaw(Map::kSize, MAP_SPACE, MAP_SPACE);
   if (!allocation.To(&result)) return allocation;
 
   // Map::cast cannot be used due to uninitialized map field.
   reinterpret_cast<Map*>(result)->set_map(raw_unchecked_meta_map());
   reinterpret_cast<Map*>(result)->set_instance_type(instance_type);
   reinterpret_cast<Map*>(result)->set_instance_size(instance_size);
   // Initialize to only containing tagged fields.
   reinterpret_cast<Map*>(result)->set_visitor_id(
       StaticVisitorBase::GetVisitorId(instance_type, instance_size, false));
@@ skipping 3992 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 }
 }  // namespace v8::internal