Do not fire timers for finalizing objects.

Source/platform/heap/Heap.cpp

Index: Source/platform/heap/Heap.cpp
diff --git a/Source/platform/heap/Heap.cpp b/Source/platform/heap/Heap.cpp
index a25225c2bec962e07edfa8b4c754650f1be0cf4e..b89a61c9a22bd28aedece0fdb0032d071ecc653a 100644
--- a/Source/platform/heap/Heap.cpp
+++ b/Source/platform/heap/Heap.cpp
@@ -2125,6 +2125,14 @@ Address Heap::checkAndMarkPointer(Visitor* visitor, Address address)
     return nullptr;
 }
 
+bool Heap::isObjectAlive(const void* objectPointer)
+{
+    if (!ThreadState::current()->isSweepingInProgress())
+        return true;
+
+    return s_markingVisitor->isMarked(objectPointer);

[haraken, 2015/01/14 14:29:08]

Hmm, what happens in the following case?

(1) Marking marks object A and B.
(2) Lazy sweeping unmarks A.
(3) isObjectAlive(X) is called.
(4) Lazy sweeping unmarks B.
(5) Lazy sweeping is complete.

In this case, isObjectAlive(X) returns false if X==A, but returns true if X==B.
This seems wrong.

[sof, 2015/01/14 14:36:19]

I suppose we can look at the page & see if it has yet to be swept. If we can
assume no cross thread access here, that would do it. 

[haraken, 2015/01/14 14:37:44]

That would work :)

Also should we use isMarked or isAlive? (I haven't studied code.)

[sof, 2015/01/14 15:53:32]

Actually, if we constrain ourselves to GC objects with finalizers, the CL as is
(ps#1) is sufficient. The method could have a better name in that case though.

Can be generalized later (but hopefully we won't have to.)

[sof, 2015/01/14 16:06:01]

Renamed to isFinalizedObjectAlive() + clarified that the predicate isn't
supported over already finalized references.

+}
+
 #if ENABLE(GC_PROFILE_MARKING)
 const GCInfo* Heap::findGCInfo(Address address)
 {