Revert "Allow partial scanning of large arrays in order to avoid"

src/spaces.cc

Index: src/spaces.cc
diff --git a/src/spaces.cc b/src/spaces.cc
index 62d826316e3f17e4bda9f60cf252ce9509d1dacc..bc1d7b09ccaa97751c50e1083c3067340a1a93ab 100644
--- a/src/spaces.cc
+++ b/src/spaces.cc
@@ -2679,10 +2679,12 @@ MaybeObject* LargeObjectSpace::AllocateRaw(int object_size,
 
   HeapObject* object = page->GetObject();
 
-  // Make the object consistent so the large object space can be traversed.
+#ifdef DEBUG
+  // Make the object consistent so the heap can be vefified in OldSpaceStep.
   reinterpret_cast<Object**>(object->address())[0] =
       heap()->fixed_array_map();
   reinterpret_cast<Object**>(object->address())[1] = Smi::FromInt(0);
+#endif
 
   heap()->incremental_marking()->OldSpaceStep(object_size);
   return object;