Serializer: attach alignment to deferred objects.

src/snapshot/serialize.h

Index: src/snapshot/serialize.h
diff --git a/src/snapshot/serialize.h b/src/snapshot/serialize.h
index 854dc27a3d1bda58a20ce6997c9695146468f497..f68ad3739a990c9e56d1296a3ad20b06fb85f4dc 100644
--- a/src/snapshot/serialize.h
+++ b/src/snapshot/serialize.h
@@ -403,6 +403,14 @@ class Deserializer: public SerializerDeserializer {
     memcpy(dest, src, sizeof(*src));
   }
 
+  void SetAlignment(byte data) {
+    DCHECK_EQ(kWordAligned, next_alignment_);
+    int alignment = data - (kAlignmentPrefix - 1);
+    DCHECK_LE(kWordAligned, alignment);
+    DCHECK_LE(alignment, kSimd128Unaligned);
+    next_alignment_ = static_cast<AllocationAlignment>(alignment);
+  }
+
   void DeserializeDeferredObjects();
 
   void FlushICacheForNewIsolate();