Object ID Ring with tests

runtime/vm/scavenger.h

Index: runtime/vm/scavenger.h
diff --git a/runtime/vm/scavenger.h b/runtime/vm/scavenger.h
index 2ff0033355f63b76e761d2555c6dd54cd8f2eb65..64cc4ceeb8b5e8d5eb591a0282b2bb185c5fec7c 100644
--- a/runtime/vm/scavenger.h
+++ b/runtime/vm/scavenger.h
@@ -103,6 +103,7 @@ class Scavenger {
   uword FirstObjectStart() const { return to_->start() | object_alignment_; }
   void Prologue(Isolate* isolate, bool invoke_api_callbacks);
   void IterateStoreBuffers(Isolate* isolate, ScavengerVisitor* visitor);
+  void IterateObjectIdTable(Isolate* isolate, ScavengerVisitor* visitor);
   void IterateRoots(Isolate* isolate,
                     ScavengerVisitor* visitor,
                     bool visit_prologue_weak_persistent_handles);
@@ -139,6 +140,8 @@ class Scavenger {
 
   void ProcessWeakTables();
 
+  void ProcessObjectIdTable();
+
   VirtualMemory* space_;
   MemoryRegion* to_;
   MemoryRegion* from_;