Use class id instead of class in subtype test cache.

runtime/vm/object.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_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 2631 matching lines @@
   intptr_t TestEntryLength() const;
 
   HEAP_OBJECT_IMPLEMENTATION(ICData, Object);
   friend class Class;
 };
 
 
 class SubtypeTestCache : public Object {
  public:
   enum Entries {
-    kInstanceClass = 0,
+    kInstanceClassId = 0,
     kInstanceTypeArguments = 1,
     kInstantiatorTypeArguments = 2,
     kTestResult = 3,
     kTestEntryLength  = 4,
   };
 
   intptr_t NumberOfChecks() const;
-  void AddCheck(const Class& instance_class,
+  void AddCheck(intptr_t class_id,
                 const AbstractTypeArguments& instance_type_arguments,
                 const AbstractTypeArguments& instantiator_type_arguments,
                 const Bool& test_result) const;
   void GetCheck(intptr_t ix,
-                Class* instance_class,
+                intptr_t* class_id,
                 AbstractTypeArguments* instance_type_arguments,
                 AbstractTypeArguments* instantiator_type_arguments,
                 Bool* test_result) const;
 
   static RawSubtypeTestCache* New();
 
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawSubtypeTestCache));
   }
 
@@ skipping 2417 matching lines @@
 }
 
 
 intptr_t Stackmap::SizeInBits() const {
   return (Smi::Value(raw_ptr()->bitmap_size_in_bytes_) * kBitsPerByte);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_