[heap] Divide available memory upon compaction tasks

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 527800f4d181bec8b8726328bb0aaed86a8adb19..f6511382a0fac54e6dcff4c0903bed79a4d2b96f 100644
--- a/src/heap/mark-compact.h
+++ b/src/heap/mark-compact.h
@@ -467,6 +467,7 @@ class MarkCompactCollector {
   bool IsSweepingCompleted();
 
   void RefillFreeList(PagedSpace* space);
+  void RefillFreeList(CompactionSpace* space);
 
   // Checks if sweeping is in progress right now on any space.
   bool sweeping_in_progress() { return sweeping_in_progress_; }
@@ -516,6 +517,8 @@ class MarkCompactCollector {
   class CompactionTask;
   class SweeperTask;
 
+  static const intptr_t kCompactionSpaceMemoryWanted = 500 * KB;
+
   explicit MarkCompactCollector(Heap* heap);
   ~MarkCompactCollector();