Ensure double alignment when deserializing.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index e38719379b6fced1a9648bf93a2d7c48a1f8db23..22ba7a9f1619cd3b3b1ab6c9bdbf838c41c139ec 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -1829,6 +1829,11 @@ static HeapObject* EnsureDoubleAligned(Heap* heap, HeapObject* object,
 }
 
 
+HeapObject* Heap::DoubleAlignForDeserialization(HeapObject* object, int size) {
+  return EnsureDoubleAligned(this, object, size);

[rmcilroy, 2014/11/26 17:44:40]

Could you add an ASSERT(object->NeedsToEnsureDoubleAlignment()) in
EnsureDoubleAligned to ensure that the list in NeedsToEnsureDoubleAlignment
keeps in sync with objects which call EnsureDoubleAligned during allocation.

[Yang, 2014/11/26 18:59:49]

Unfortunately, at this point, the object is no more than an allocation. It
doesn't have a map yet, so we can't check for its object type.

I could add a DCHECK(object->NeedsToEnsureDoubleAlignment) at the call sites 
(AllocateFixedDoubleArray etc.) after the map is set, though.

[rmcilroy, 2014/11/26 19:24:46]

Right enough.  Your suggestion stgt. It doesn't quite capture the check, but
would hopefully help someone realise they should add to this list if adding a
new double aligned object.

+}
+
+
 enum LoggingAndProfiling {
   LOGGING_AND_PROFILING_ENABLED,
   LOGGING_AND_PROFILING_DISABLED