Add support for object pool

runtime/vm/object.h

Index: runtime/vm/object.h
===================================================================
--- runtime/vm/object.h	(revision 18597)
+++ runtime/vm/object.h	(working copy)
@@ -2226,6 +2226,7 @@
  public:
   intptr_t size() const { return raw_ptr()->size_; }
   RawCode* code() const { return raw_ptr()->code_; }
+  RawArray* object_pool() const { return raw_ptr()->object_pool_; }
 
   uword EntryPoint() const {
     return reinterpret_cast<uword>(raw_ptr()) + HeaderSize();
@@ -2263,9 +2264,12 @@
   void set_size(intptr_t size) const {
     raw_ptr()->size_ = size;
   }
-  void set_code(RawCode* code) {
+  void set_code(RawCode* code) const {
     raw_ptr()->code_ = code;
   }
+  void set_object_pool(RawArray* object_pool) const {
+    raw_ptr()->object_pool_ = object_pool;
+  }
 
   // New is a private method as RawInstruction and RawCode objects should
   // only be created using the Code::FinalizeCode method. This method creates