[heap] Use size_t in free list and evacuation candidate selection.

src/heap/mark-compact.h

Index: src/heap/mark-compact.h
diff --git a/src/heap/mark-compact.h b/src/heap/mark-compact.h
index 2cbb369f763e0e2cfc6eaaa2cca93d893dbace7d..9456743c73f5d36b620d731e462aeda0477b5854 100644
--- a/src/heap/mark-compact.h
+++ b/src/heap/mark-compact.h
@@ -504,9 +504,9 @@ class MarkCompactCollector {
   bool WillBeDeoptimized(Code* code);
   void ClearInvalidRememberedSetSlots();
 
-  void ComputeEvacuationHeuristics(int area_size,
+  void ComputeEvacuationHeuristics(size_t area_size,
                                    int* target_fragmentation_percent,
-                                   int* max_evacuated_bytes);
+                                   size_t* max_evacuated_bytes);
 
   void VisitAllObjects(HeapObjectVisitor* visitor);