Ensure double alignment when deserializing.

src/heap/heap.h

 // 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.
 
 #ifndef V8_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 
 #include "src/allocation.h"
@@ skipping 1708 matching lines @@
   // size, pretenuring decision, and preferred old-space.
   static AllocationSpace SelectSpace(int object_size,
                                      AllocationSpace preferred_old_space,
                                      PretenureFlag pretenure) {
     DCHECK(preferred_old_space == OLD_POINTER_SPACE ||
            preferred_old_space == OLD_DATA_SPACE);
     if (object_size > Page::kMaxRegularHeapObjectSize) return LO_SPACE;
     return (pretenure == TENURED) ? preferred_old_space : NEW_SPACE;
   }
 
+  HeapObject* DoubleAlignForDeserialization(HeapObject* object, int size);
+
   // Allocate an uninitialized object.  The memory is non-executable if the
   // hardware and OS allow.  This is the single choke-point for allocations
   // performed by the runtime and should not be bypassed (to extend this to
   // inlined allocations, use the Heap::DisableInlineAllocation() support).
   MUST_USE_RESULT inline AllocationResult AllocateRaw(
       int size_in_bytes, AllocationSpace space, AllocationSpace retry_space);
 
   // Allocates a heap object based on the map.
   MUST_USE_RESULT AllocationResult
       Allocate(Map* map, AllocationSpace space,
@@ skipping 833 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_H_