[heap] Fix -Wsign-compare warnings

src/heap/spaces.cc

Index: src/heap/spaces.cc
diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index e485e189c6534abe76080f2969c0f0678a3f6c01..b6097280c48441cf95289c0bb4506aaf2cae3d91 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -2852,7 +2852,7 @@ HeapObject* PagedSpace::SlowAllocateRaw(int size_in_bytes) {
 
   if (heap()->ShouldExpandOldGenerationOnAllocationFailure() && Expand()) {
     DCHECK((CountTotalPages() > 1) ||
-           (size_in_bytes <= free_list_.Available()));
+           (static_cast<size_t>(size_in_bytes) <= free_list_.Available()));
     return free_list_.Allocate(static_cast<size_t>(size_in_bytes));
   }