Moves the top_ and end_ words of the Scavenger into mutator thread.

runtime/vm/heap.h

Index: runtime/vm/heap.h
diff --git a/runtime/vm/heap.h b/runtime/vm/heap.h
index 6c68d0fcba67c33c15698241232685e729f7627c..a960b488d89224308109f8fa6b39703971721e87 100644
--- a/runtime/vm/heap.h
+++ b/runtime/vm/heap.h
@@ -94,6 +94,7 @@ class Heap {
   bool DataContains(uword addr) const;
 
   void IterateObjects(ObjectVisitor* visitor) const;
+  void IterateNewObjects(ObjectVisitor* visitor) const;
   void IterateOldObjects(ObjectVisitor* visitor) const;
   void IterateOldObjectsNoImagePages(ObjectVisitor* visitor) const;
   void IterateObjectPointers(ObjectVisitor* visitor) const;
@@ -136,8 +137,6 @@ class Heap {
   }
 
   // Accessors for inlined allocation in generated code.
-  static intptr_t TopOffset(Space space);
-  static intptr_t EndOffset(Space space);
 
   // Initialize the heap and register it with the isolate.
   static void Init(Isolate* isolate,
@@ -343,7 +342,7 @@ class Heap {
   Isolate* isolate_;
 
   // The different spaces used for allocation.
-  ALIGN8 Scavenger new_space_;
+  Scavenger new_space_;
   PageSpace old_space_;
 
   WeakTable* new_weak_tables_[kNumWeakSelectors];