[cctest] Fix invalid assumption in test-unboxed-doubles

test/cctest/test-unboxed-doubles.cc

 // Copyright 2014 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.
 
 #include <stdlib.h>
 #include <utility>
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
@@ skipping 1393 matching lines @@
   // |double_descriptor|. Call GC and ensure that it did not crash during
   // store buffer entries updating.
 
   Handle<JSObject> obj;
   Handle<HeapObject> obj_value;
   {
     AlwaysAllocateScope always_allocate(isolate);
     obj = factory->NewJSObjectFromMap(map, TENURED);
     CHECK(old_space->Contains(*obj));
 
-    obj_value = factory->NewJSArray(32 * KB, FAST_HOLEY_ELEMENTS);
+    obj_value = factory->NewHeapNumber(0.);
   }
 
   CHECK(heap->InNewSpace(*obj_value));
 
   {
     FieldIndex index = FieldIndex::ForDescriptor(*map, tagged_descriptor);
     const int n = 153;
     for (int i = 0; i < n; i++) {
       obj->FastPropertyAtPut(index, *obj_value);
     }
@@ skipping 154 matching lines @@
 
 // TODO(ishell): add respective tests for property kind reconfiguring from
 // accessor field to double, once accessor fields are supported by
 // Map::ReconfigureProperty().
 
 
 // TODO(ishell): add respective tests for fast property removal case once
 // Map::ReconfigureProperty() supports that.
 
 #endif