Unify promotion and allocation limit computation.

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index 2aac8b0dd01ed23c7f95363b33678849067d6191..27f48d3a662158f4d0679d83b00144812332a659 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -3817,8 +3817,9 @@ void MarkCompactCollector::SweepSpace(PagedSpace* space, SweeperType sweeper) {
 
   intptr_t old_space_size = heap()->PromotedSpaceSizeOfObjects();
   intptr_t space_left =
-      Min(heap()->OldGenPromotionLimit(old_space_size),
-          heap()->OldGenAllocationLimit(old_space_size)) - old_space_size;
+      Min(heap()->OldGenLimit(old_space_size, Heap::kMinPromotionLimit),
+          heap()->OldGenLimit(old_space_size, Heap::kMinAllocationLimit)) -
+      old_space_size;
 
   while (it.has_next()) {
     Page* p = it.next();