Fix PagedSpace size accounting.

R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/392163003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22433 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mark-compact.cc

@@ -3947,6 +3947,7 @@ static intptr_t Free(PagedSpace* space,
   if (mode == MarkCompactCollector::SWEEP_ON_MAIN_THREAD) {
     return space->Free(start, size);
   } else {
+    // TODO(hpayer): account for wasted bytes in concurrent sweeping too.
     return size - free_list->Free(start, size);
   }
 }

src/spaces.h

@@ -1457,9 +1457,8 @@ class AllocationStats BASE_EMBEDDED {
 
   // Waste free bytes (available -> waste).
   void WasteBytes(int size_in_bytes) {
-    size_ -= size_in_bytes;
+    ASSERT(size_in_bytes >= 0);
     waste_ += size_in_bytes;
-    ASSERT(size_ >= 0);
   }
 
  private:
@@ -1857,7 +1856,8 @@ class PagedSpace : public Space {
   // no attempt to add area to free list is made.
   int Free(Address start, int size_in_bytes) {
     int wasted = free_list_.Free(start, size_in_bytes);
-    accounting_stats_.DeallocateBytes(size_in_bytes - wasted);
+    accounting_stats_.DeallocateBytes(size_in_bytes);
+    accounting_stats_.WasteBytes(wasted);
     return size_in_bytes - wasted;
   }