Rescan cells at the end of mark-sweep. This means they don't need a

src/mark-compact.cc

Index: src/mark-compact.cc
===================================================================
--- src/mark-compact.cc	(revision 10174)
+++ src/mark-compact.cc	(working copy)
@@ -2081,6 +2081,22 @@
 
   PrepareForCodeFlushing();
 
+  // There is no write barrier on cells so we have to scan them now at the end
+  // of the incremental sweeping.

[Vyacheslav Egorov (Chromium), 2011/12/06 15:28:15]

at the end of incremental marking

+  {

[Vyacheslav Egorov (Chromium), 2011/12/06 15:28:15]

Please check that we actually _had_ incremental marking, otherwise we just waste
time.

+    HeapObjectIterator cell_iterator(heap()->cell_space());
+    HeapObject* cell;
+    while ((cell = cell_iterator.Next()) != NULL) {
+      ASSERT(cell->IsJSGlobalPropertyCell());
+      if (IsMarked(cell)) {
+        int offset = JSGlobalPropertyCell::kValueOffset;
+        StaticMarkingVisitor::VisitPointer(
+            heap(),
+            reinterpret_cast<Object**>(cell->address() + offset));
+      }
+    }
+  }
+
   RootMarkingVisitor root_visitor(heap());
   MarkRoots(&root_visitor);