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

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
diff --git a/src/x64/lithium-x64.h b/src/x64/lithium-x64.h
index c1da8044fb8728fe27e579d8dbe4962305c15585..42f4d84f3e55d457d3b80ad7d7da4bdb0c411be6 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -74,7 +74,6 @@ class LCodeGen;
   V(ClampIToUint8)                              \
   V(ClampTToUint8)                              \
   V(ClassOfTestAndBranch)                       \
-  V(CmpConstantEqAndBranch)                     \
   V(CompareNumericAndBranch)                    \
   V(CmpObjectEqAndBranch)                       \
   V(CmpMapAndBranch)                            \
@@ -831,20 +830,6 @@ class LCmpObjectEqAndBranch: public LControlInstruction<2, 0> {
 };
 
 
-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) {