Update comments in the global handles interface.

src/global-handles.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 144 matching lines @@
   // Tells whether global handle is weak.
   static bool IsWeak(Object** location);
 
   // Process pending weak handles.
   // Returns true if next major GC is likely to collect more garbage.
   bool PostGarbageCollectionProcessing(GarbageCollector collector);
 
   // Iterates over all strong handles.
   void IterateStrongRoots(ObjectVisitor* v);
 
-  // Iterates over all strong and dependent handles.
-  void IterateNewSpaceStrongAndDependentRoots(ObjectVisitor* v);
-
   // Iterates over all handles.
   void IterateAllRoots(ObjectVisitor* v);
 
   // Iterates over all handles that have embedder-assigned class ID.
   void IterateAllRootsWithClassIds(ObjectVisitor* v);
 
   // Iterates over all weak roots in heap.
   void IterateWeakRoots(ObjectVisitor* v);
 
-  // Iterates over all weak independent roots in heap.
-  void IterateNewSpaceWeakIndependentRoots(ObjectVisitor* v);
-
   // Iterates over weak roots that are bound to a given callback.
   void IterateWeakRoots(WeakReferenceGuest f,
                         WeakReferenceCallback callback);
 
   // Find all weak handles satisfying the callback predicate, mark
   // them as pending.
   void IdentifyWeakHandles(WeakSlotCallback f);
 
-  // Find all weak independent handles satisfying the callback predicate, mark
-  // them as pending.
+  // NOTE: Three ...NewSpace... functions below are used during
+  // scavenge collections and iterate over sets of handles that are
+  // guaranteed to contain all handles holding new space objects (but
+  // may also include old space objects).
+
+  // 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.
   void IdentifyNewSpaceWeakIndependentHandles(WeakSlotCallbackWithHeap f);
 
+  // Iterates over weak 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.
   void AddObjectGroup(Object*** handles,
                       size_t length,
                       v8::RetainedObjectInfo* info);
 
   // Add an implicit references' group.
   // Should be only used in GC callback function before a collection.
   // All groups are destroyed after a mark-compact collection.
@@ skipping 61 matching lines @@
 
   friend class Isolate;
 
   DISALLOW_COPY_AND_ASSIGN(GlobalHandles);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_GLOBAL_HANDLES_H_