Remove HCompareConstantEqAndBranch (never used), and its corresponding Lithium instructions.

src/x64/lithium-x64.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 56 matching lines @@
   V(CheckInstanceType)                          \
   V(CheckMaps)                                  \
   V(CheckMapValue)                              \
   V(CheckNonSmi)                                \
   V(CheckPrototypeMaps)                         \
   V(CheckSmi)                                   \
   V(ClampDToUint8)                              \
   V(ClampIToUint8)                              \
   V(ClampTToUint8)                              \
   V(ClassOfTestAndBranch)                       \
-  V(CmpConstantEqAndBranch)                     \
   V(CompareNumericAndBranch)                    \
   V(CmpObjectEqAndBranch)                       \
   V(CmpMapAndBranch)                            \
   V(CmpT)                                       \
   V(ConstantD)                                  \
   V(ConstantI)                                  \
   V(ConstantS)                                  \
   V(ConstantT)                                  \
   V(Context)                                    \
   V(DateField)                                  \
@@ skipping 736 matching lines @@
   }
 
   LOperand* left() { return inputs_[0]; }
   LOperand* right() { return inputs_[1]; }
 
   DECLARE_CONCRETE_INSTRUCTION(CmpObjectEqAndBranch,
                                "cmp-object-eq-and-branch")
 };
 
 
-class LCmpConstantEqAndBranch: public LControlInstruction<1, 0> {
- public:
-  explicit LCmpConstantEqAndBranch(LOperand* left) {
-    inputs_[0] = left;
-  }
-
-  LOperand* left() { return inputs_[0]; }
-
-  DECLARE_CONCRETE_INSTRUCTION(CmpConstantEqAndBranch,
-                               "cmp-constant-eq-and-branch")
-  DECLARE_HYDROGEN_ACCESSOR(CompareConstantEqAndBranch)
-};
-
-
 class LIsObjectAndBranch: public LControlInstruction<1, 0> {
  public:
   explicit LIsObjectAndBranch(LOperand* value) {
     inputs_[0] = value;
   }
 
   LOperand* value() { return inputs_[0]; }
 
   DECLARE_CONCRETE_INSTRUCTION(IsObjectAndBranch, "is-object-and-branch")
   DECLARE_HYDROGEN_ACCESSOR(IsObjectAndBranch)
@@ skipping 1862 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::int
 
 #endif  // V8_X64_LITHIUM_X64_H_