MIPS: Fix bad RegisterConfiguration usage in InstructionSequence unit tests.

src/compiler/instruction.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_INSTRUCTION_H_
 #define V8_COMPILER_INSTRUCTION_H_
 
 #include <deque>
 #include <iosfwd>
 #include <map>
@@ skipping 1487 matching lines @@
   void Print() const;
 
   void PrintBlock(const RegisterConfiguration* config, int block_id) const;
   void PrintBlock(int block_id) const;
 
   void ValidateEdgeSplitForm() const;
   void ValidateDeferredBlockExitPaths() const;
   void ValidateDeferredBlockEntryPaths() const;
   void ValidateSSA() const;
 
+  const RegisterConfiguration* GetRegisterConfigurationForTesting();
+
  private:
   friend V8_EXPORT_PRIVATE std::ostream& operator<<(
       std::ostream& os, const PrintableInstructionSequence& code);
 
   typedef ZoneMap<const Instruction*, SourcePosition> SourcePositionMap;
 
   Isolate* isolate_;
   Zone* const zone_;
   InstructionBlocks* const instruction_blocks_;
   SourcePositionMap source_positions_;
@@ skipping 18 matching lines @@
 };
 
 V8_EXPORT_PRIVATE std::ostream& operator<<(
     std::ostream& os, const PrintableInstructionSequence& code);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_H_