Remove the unused HElementsKind instruction.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 0e33c82cb482bc2b357b6fe1e9772dd28e98ab18..d92e7ed89af99fe6b0d7f350ba98882ee0f717c1 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -109,7 +109,6 @@ class LChunkBuilder;
   V(Deoptimize)                                \
   V(Div)                                       \
   V(DummyUse)                                  \
-  V(ElementsKind)                              \
   V(EnterInlined)                              \
   V(EnvironmentMarker)                         \
   V(ForceRepresentation)                       \
@@ -2539,28 +2538,6 @@ class HMapEnumLength V8_FINAL : public HUnaryOperation {
 };
 
 
-class HElementsKind V8_FINAL : public HUnaryOperation {
- public:
-  explicit HElementsKind(HValue* value) : HUnaryOperation(value) {
-    set_representation(Representation::Integer32());
-    SetFlag(kUseGVN);
-    SetGVNFlag(kDependsOnElementsKind);
-  }
-
-  virtual Representation RequiredInputRepresentation(int index) V8_OVERRIDE {
-    return Representation::Tagged();
-  }
-
-  DECLARE_CONCRETE_INSTRUCTION(ElementsKind)
-
- protected:
-  virtual bool DataEquals(HValue* other) V8_OVERRIDE { return true; }
-
- private:
-  virtual bool IsDeletable() const V8_OVERRIDE { return true; }
-};
-
-
 class HUnaryMathOperation V8_FINAL : public HTemplateInstruction<2> {
  public:
   static HInstruction* New(Zone* zone,