[gn] Enable stricter build flags

src/field-index-inl.h

 // 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.
 
 #ifndef V8_FIELD_INDEX_INL_H_
 #define V8_FIELD_INDEX_INL_H_
 
 #include "src/field-index.h"
 
 namespace v8 {
@@ skipping 25 matching lines @@
   }
   return FieldIndex(is_inobject,
                     property_index + first_inobject_offset / kPointerSize,
                     is_double, inobject_properties, first_inobject_offset);
 }
 
 // Takes an index as computed by GetLoadByFieldIndex and reconstructs a
 // FieldIndex object from it.
 inline FieldIndex FieldIndex::ForLoadByFieldIndex(Map* map, int orig_index) {
   int field_index = orig_index;
-  int is_inobject = true;
+  bool is_inobject = true;
   bool is_double = field_index & 1;
   int first_inobject_offset = 0;
   field_index >>= 1;
   if (field_index < 0) {
     field_index = -(field_index + 1);
     is_inobject = false;
     first_inobject_offset = FixedArray::kHeaderSize;
     field_index += FixedArray::kHeaderSize / kPointerSize;
   } else {
     first_inobject_offset = map->GetInObjectPropertyOffset(0);
@@ skipping 36 matching lines @@
 }
 
 inline FieldIndex FieldIndex::FromFieldAccessStubKey(int key) {
   return FieldIndex(key);
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif