Do not fire timers for finalizing objects.

Source/platform/heap/Heap.h

Index: Source/platform/heap/Heap.h
diff --git a/Source/platform/heap/Heap.h b/Source/platform/heap/Heap.h
index 52ecf0673835cac59fe74693cd537382b00f4b97..6d85b0078cfafba436af5344f2233dc0ceb4df1c 100644
--- a/Source/platform/heap/Heap.h
+++ b/Source/platform/heap/Heap.h
@@ -401,11 +401,26 @@ public:
     bool terminating() { return m_terminating; }
     void setTerminating() { m_terminating = true; }
 
+    void markAsLazilySwept();
+    bool hasBeenLazilySwept() const;
+
 private:
     PageMemory* m_storage;
     ThreadState* m_threadState;
     // Whether the page is part of a terminating thread or not.
     bool m_terminating;
+
+protected:
+    // Track the (lazy) sweeping state of a page. The page's
+    // ThreadState keeps a sweep token value, with the page being
+    // updated with that value as it is swept.
+    //
+    // By comparing the ThreadState's current sweep token value with
+    // the page's sweep status, its swept/unswept status can
+    // readily be determined.
+    //
+    // 0 represents the unused/no-toggle state.
+    unsigned m_sweepStatus : 2;
 };
 
 class HeapPage final : public BaseHeapPage {
@@ -818,6 +833,15 @@ public:
     static bool containedInHeapOrOrphanedPage(void*);
 #endif
 
+    // Is the finalizable GC object still alive? If no GC is in progress,
+    // it must be true. If a lazy sweep is in progress, it will be true if
+    // the object has been marked. An unmarked object is otherwise
+    // slated for finalization once swept, and false is returned.
+    //
+    // The predicate must not be used with already finalized object
+    // references.
+    static bool isFinalizedObjectAlive(const void*);
+
     // Push a trace callback on the marking stack.
     static void pushTraceCallback(void* containerObject, TraceCallback);