Provide API support for weak handles and post-mortem finalization.

runtime/vm/handles.h

Index: runtime/vm/handles.h
diff --git a/runtime/vm/handles.h b/runtime/vm/handles.h
index 94b5fd467985f2837c428ac338ff59c46f0fd10f..4eb512922aa5931aba87b41f47c2a4f112b31fd5 100644
--- a/runtime/vm/handles.h
+++ b/runtime/vm/handles.h
@@ -60,7 +60,7 @@ class ObjectPointerVisitor;
 
 class HandleVisitor {
  public:
-  virtual void Visit(uword* addr) = 0;
+  virtual void VisitHandle(uword* addr) = 0;

[Ivan Posva, 2012/01/12 23:30:38]

uword is already an address type, so please just use "VisitHandle(uword
handle)".

Also I can imagine that in the future we might need to pass a kind of weak
handle.

[cshapiro, 2012/01/13 01:30:03]

Done (here and in the callers).

 
   virtual ~HandleVisitor() {
   }
@@ -82,7 +82,7 @@ class Handles {
   // Visit all object pointers stored in the various handles.
   void VisitObjectPointers(ObjectPointerVisitor* visitor);
 
-  // Visits all of the various handles.
+  // Visit all of the various handles.
   void Visit(HandleVisitor* visitor);
 
   // Allocates a handle in the current handle scope. This handle is valid only