Update V8 to r5295 as required by WebKit r65615

Change-Id: I1d72d4990703e88b7798919c7a53e12ebf76958a
diff --git a/src/serialize.h b/src/serialize.h
index 6a318f1..80be50d 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -248,7 +248,7 @@
   }
 
   static int partial_snapshot_cache_length_;
-  static const int kPartialSnapshotCacheCapacity = 1300;
+  static const int kPartialSnapshotCacheCapacity = 1400;
   static Object* partial_snapshot_cache_[];
 };
 
@@ -536,7 +536,8 @@
     // would cause dupes.
     ASSERT(!o->IsScript());
     return o->IsString() || o->IsSharedFunctionInfo() ||
-           o->IsHeapNumber() || o->IsCode();
+           o->IsHeapNumber() || o->IsCode() ||
+           o->map() == Heap::fixed_cow_array_map();
   }
 
  private: