Allow collection of DOM objects in minor GC cycles.

src/global-handles.h

Index: src/global-handles.h
diff --git a/src/global-handles.h b/src/global-handles.h
index 866317ee139977a199c89ccb07d6be478bed073a..482baef3fa4b62a0c05be194a94163967a4e18cb 100644
--- a/src/global-handles.h
+++ b/src/global-handles.h
@@ -155,6 +155,9 @@ class GlobalHandles {
   // Clear the weakness of a global handle.
   void MarkIndependent(Object** location);
 
+  // Mark the reference to this object externaly unreachable.
+  void MarkPartiallyDependent(Object** location);
+
   static bool IsIndependent(Object** location);
 
   // Tells whether global handle is near death.
@@ -195,16 +198,17 @@ class GlobalHandles {
   // Iterates over strong and dependent handles. See the node above.
   void IterateNewSpaceStrongAndDependentRoots(ObjectVisitor* v);
 
-  // Finds weak independent handles satisfying the callback predicate
-  // and marks them as pending. See the note above.
+  // Finds weak independent or partially independent handles satisfying
+  // the callback predicate and marks them as pending. See the note above.
   void IdentifyNewSpaceWeakIndependentHandles(WeakSlotCallbackWithHeap f);
 
-  // Iterates over weak independent handles. See the note above.
+  // Iterates over weak independent or partially independent handles.
+  // See the note above.
   void IterateNewSpaceWeakIndependentRoots(ObjectVisitor* v);
 
   // Add an object group.
   // Should be only used in GC callback function before a collection.
-  // All groups are destroyed after a mark-compact collection.
+  // All groups are destroyed after a garbage collection.
   void AddObjectGroup(Object*** handles,
                       size_t length,
                       v8::RetainedObjectInfo* info);