[runtime] Remove the redundant %_IsObject intrinsic.

src/mips64/lithium-codegen-mips64.h

 // Copyright 2012 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_MIPS_LITHIUM_CODEGEN_MIPS_H_
 #define V8_MIPS_LITHIUM_CODEGEN_MIPS_H_
 
 #include "src/deoptimizer.h"
 #include "src/lithium-codegen.h"
 #include "src/mips64/lithium-gap-resolver-mips64.h"
@@ skipping 287 matching lines @@
   // true and false label should be made, to optimize fallthrough.
   // Returns two registers in cmp1 and cmp2 that can be used in the
   // Branch instruction after EmitTypeofIs.
   Condition EmitTypeofIs(Label* true_label,
                          Label* false_label,
                          Register input,
                          Handle<String> type_name,
                          Register* cmp1,
                          Operand* cmp2);
 
-  // Emits optimized code for %_IsObject(x).  Preserves input register.
-  // Returns the condition on which a final split to
-  // true and false label should be made, to optimize fallthrough.
-  Condition EmitIsObject(Register input,
-                         Register temp1,
-                         Register temp2,
-                         Label* is_not_object,
-                         Label* is_object);
-
   // Emits optimized code for %_IsString(x).  Preserves input register.
   // Returns the condition on which a final split to
   // true and false label should be made, to optimize fallthrough.
   Condition EmitIsString(Register input,
                          Register temp1,
                          Label* is_not_string,
                          SmiCheck check_needed);
 
   // Emits optimized code for %_IsConstructCall().
   // Caller should branch on equal condition.
@@ skipping 107 matching lines @@
   LCodeGen* codegen_;
   Label entry_;
   Label exit_;
   Label* external_exit_;
   int instruction_index_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_MIPS_LITHIUM_CODEGEN_MIPS_H_