[runtime] Remove the redundant %_IsObject intrinsic.

src/x64/lithium-codegen-x64.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_X64_LITHIUM_CODEGEN_X64_H_
 #define V8_X64_LITHIUM_CODEGEN_X64_H_
 
 #include "src/x64/lithium-x64.h"
 
 #include "src/base/logging.h"
@@ skipping 247 matching lines @@
   template <class InstrType>
   void EmitFalseBranch(InstrType instr, Condition cc);
   void EmitNumberUntagD(LNumberUntagD* instr, Register input,
                         XMMRegister result, NumberUntagDMode mode);
 
   // Emits optimized code for typeof x == "y".  Modifies input register.
   // Returns the condition on which a final split to
   // true and false label should be made, to optimize fallthrough.
   Condition EmitTypeofIs(LTypeofIsAndBranch* instr, Register input);
 
-  // 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,
-                         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 105 matching lines @@
   Label entry_;
   Label exit_;
   Label done_;
   Label* external_exit_;
   int instruction_index_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_LITHIUM_CODEGEN_X64_H_