Filter old to new references when moving parts of an object.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index 9281fa9d72e354bfc4e16d035bcc14e71eb7a158..b70595f69909e9257158ffb5bb9aa00415cb85b0 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -525,6 +525,9 @@ class Heap {
     return NULL;
   }
 
+  void MoveElements(FixedArray* dst, int dst_index, FixedArray* src,

[Michael Starzinger, 2013/01/08 13:13:00]

This method needs a comment explaining it's semantics. Also I would move it down
to the other FixedArray methods (e.g. somewhere around CopyFixedArray).

The assumption is that whenever we move values in an object that "src == dst"
holds. So I think it makes more sence to have an API that just takes one object
pointer, two offsets into it and one length. This also makes further
optimizations easier. WDYT?

[Hannes Payer (out of office), 2013/01/09 09:32:46]

Done.

+                    int src_index, int len);
+
   bool always_allocate() { return always_allocate_scope_depth_ != 0; }
   Address always_allocate_scope_depth_address() {
     return reinterpret_cast<Address>(&always_allocate_scope_depth_);