Add LoadTaggedClassIdMayBeSmi to assembly and improve performance of inline cache stubs.

runtime/vm/assembler_mips.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_MIPS_H_
 #define VM_ASSEMBLER_MIPS_H_
 
 #ifndef VM_ASSEMBLER_H_
 #error Do not include assembler_mips.h directly; use assembler.h instead.
 #endif
@@ skipping 1165 matching lines @@
 
   // Compares rn with the object. Returns results in rd1 and rd2.
   // rd1 is 1 if rn < object. rd2 is 1 if object < rn. Since both cannot be
   // 1, rd1 == rd2 (== 0) iff rn == object.
   void CompareObject(Register rd1, Register rd2,
                      Register rn, const Object& object);
 
   void LoadClassId(Register result, Register object);
   void LoadClassById(Register result, Register class_id);
   void LoadClass(Register result, Register object);
+  void LoadTaggedClassIdMayBeSmi(Register result, Register object);
 
   void StoreIntoObject(Register object,  // Object we are storing into.
                        const Address& dest,  // Where we are storing into.
                        Register value,  // Value we are storing.
                        bool can_value_be_smi = true);
 
   void StoreIntoObjectNoBarrier(Register object,
                                 const Address& dest,
                                 Register value);
   void StoreIntoObjectNoBarrier(Register object,
@@ skipping 147 matching lines @@
                                   Register value,
                                   Label* no_update);
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(Assembler);
 };
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_MIPS_H_