Split nodes and edges into separate arrays in heap profiler.

src/list.h

Index: src/list.h
diff --git a/src/list.h b/src/list.h
index a210dfb1b807e19f9e8659e39faaf5f09ee68cd0..7350c0d44ecc57fd4d4915f499c4656544b860a3 100644
--- a/src/list.h
+++ b/src/list.h
@@ -117,6 +117,9 @@ class List {
   // pointer type. Returns the removed element.
   INLINE(T RemoveLast()) { return Remove(length_ - 1); }
 
+  // Deletes current list contents and allocates space for 'length' elements.
+  INLINE(void Allocate(int length));
+
   // Clears the list by setting the length to zero. Even if T is a
   // pointer type, clearing the list doesn't delete the entries.
   INLINE(void Clear());