Make subtype test stubs isolate-specific.

runtime/vm/assembler_ia32.h

 // Copyright (c) 2013, 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_ASSEMBLER_IA32_H_
 #define VM_ASSEMBLER_IA32_H_
 
 #ifndef VM_ASSEMBLER_H_
 #error Do not include assembler_ia32.h directly; use assembler.h instead.
 #endif
@@ skipping 672 matching lines @@
   void EnterCallRuntimeFrame(intptr_t frame_space);
   void LeaveCallRuntimeFrame();
 
   void CallRuntime(const RuntimeEntry& entry, intptr_t argument_count);
 
   /*
    * Loading and comparing classes of objects.
    */
   void LoadClassId(Register result, Register object);
 
-  void LoadClassById(Register result, Register class_id);
+  void LoadClassById(Register result, Register class_id, Isolate* isolate);
 
-  void LoadClass(Register result, Register object, Register scratch);
+  void LoadClass(Register result,
+                 Register object,
+                 Register scratch,
+                 Isolate* isolate);
 
   void CompareClassId(Register object, intptr_t class_id, Register scratch);
 
   void LoadTaggedClassIdMayBeSmi(Register result,
                                  Register object);
 
   void SmiUntagOrCheckClass(Register object,
                             intptr_t class_id,
                             Register scratch,
                             Label* is_smi);
@@ skipping 242 matching lines @@
 }
 
 
 inline void Assembler::EmitOperandSizeOverride() {
   EmitUint8(0x66);
 }
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_IA32_H_