[heap] Fix -Wsign-compare warnings

src/heap/mark-compact.cc

 // Copyright 2012 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 "src/heap/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 3313 matching lines @@
   // Clear invalid typed slots after collection all free ranges.
   if (slots_clearing_mode == CLEAR_TYPED_SLOTS) {
     p->typed_old_to_new_slots()->RemoveInvaldSlots(free_ranges);
   }
 
   // Clear the mark bits of that page and reset live bytes count.
   p->ClearLiveness();
 
   p->concurrent_sweeping_state().SetValue(Page::kSweepingDone);
   if (free_list_mode == IGNORE_FREE_LIST) return 0;
-  return FreeList::GuaranteedAllocatable(static_cast<int>(max_freed_bytes));
+  return static_cast<int>(FreeList::GuaranteedAllocatable(max_freed_bytes));
 }
 
 void MarkCompactCollector::InvalidateCode(Code* code) {
   Page* page = Page::FromAddress(code->address());
   Address start = code->instruction_start();
   Address end = code->address() + code->Size();
 
   RememberedSet<OLD_TO_NEW>::RemoveRangeTyped(page, start, end);
 
   if (heap_->incremental_marking()->IsCompacting() &&
@@ skipping 576 matching lines @@
       // The target is always in old space, we don't have to record the slot in
       // the old-to-new remembered set.
       DCHECK(!heap()->InNewSpace(target));
       RecordRelocSlot(host, &rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8