Fixes a couple problems with GC of unoptimized code.

runtime/vm/megamorphic_cache_table.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_MEGAMORPHIC_CACHE_TABLE_H_
 #define VM_MEGAMORPHIC_CACHE_TABLE_H_
 
 #include "vm/allocation.h"
 
 namespace dart {
 
 class Array;
 class Function;
 class ObjectPointerVisitor;
 class RawArray;
 class RawFunction;
+class RawCode;
 class RawMegamorphicCache;
 class RawString;
 class String;
 
 class MegamorphicCacheTable {
  public:
   MegamorphicCacheTable();
   ~MegamorphicCacheTable();
 
-  RawFunction* miss_handler() const { return miss_handler_; }
+  RawFunction* miss_handler() const { return miss_handler_function_; }
   void InitMissHandler();
 
   RawMegamorphicCache* Lookup(const String& name, const Array& descriptor);
 
   void VisitObjectPointers(ObjectPointerVisitor* visitor);
 
   void PrintSizes();
 
  private:
   struct Entry {
     RawString* name;
     RawArray* descriptor;
     RawMegamorphicCache* cache;
   };
 
   static const int kCapacityIncrement = 128;
 
-  RawFunction* miss_handler_;
+  RawFunction* miss_handler_function_;
+  RawCode* miss_handler_code_;
   intptr_t capacity_;
   intptr_t length_;
   Entry* table_;
 
   DISALLOW_COPY_AND_ASSIGN(MegamorphicCacheTable);
 };
 
 }  // namespace dart
 
 #endif  // VM_MEGAMORPHIC_CACHE_TABLE_H_