[heap] Fix -Wsign-compare warnings

test/cctest/heap/test-heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5696 matching lines @@
   Heap* heap = isolate->heap();
 
   Handle<Map> map1 = Map::Create(isolate, 1);
   Handle<String> name = factory->NewStringFromStaticChars("foo");
   name = factory->InternalizeString(name);
   Handle<Map> map2 =
       Map::CopyWithField(map1, name, FieldType::Any(isolate), NONE,
                          Representation::Tagged(), OMIT_TRANSITION)
           .ToHandleChecked();
 
-  int desired_offset = Page::kPageSize - map1->instance_size();
+  size_t desired_offset = Page::kPageSize - map1->instance_size();
 
   // Allocate padding objects in old pointer space so, that object allocated
   // afterwards would end at the end of the page.
   heap::SimulateFullSpace(heap->old_space());
-  int padding_size = desired_offset - Page::kObjectStartOffset;
-  heap::CreatePadding(heap, padding_size, TENURED);
+  size_t padding_size = desired_offset - Page::kObjectStartOffset;
+  heap::CreatePadding(heap, static_cast<int>(padding_size), TENURED);
 
   Handle<JSObject> o = factory->NewJSObjectFromMap(map1, TENURED);
   o->set_properties(*factory->empty_fixed_array());
 
   // Ensure that the object allocated where we need it.
   Page* page = Page::FromAddress(o->address());
   CHECK_EQ(desired_offset, page->Offset(o->address()));
 
   // Now we have an object right at the end of the page.
 
@@ skipping 1266 matching lines @@
       SlotSet::FREE_EMPTY_BUCKETS);
   slots[chunk->area_end() - kPointerSize] = false;
   RememberedSet<OLD_TO_NEW>::Iterate(chunk, [&slots](Address addr) {
     CHECK(slots[addr]);
     return KEEP_SLOT;
   });
 }
 
 }  // namespace internal
 }  // namespace v8