[crankshaft] Remove the useless HCallStub instruction.

src/crankshaft/x64/lithium-x64.h

Index: src/crankshaft/x64/lithium-x64.h
diff --git a/src/crankshaft/x64/lithium-x64.h b/src/crankshaft/x64/lithium-x64.h
index e00ae0a1ab3b2fabb4df227514564f4c45c8400a..76eac9f5c618265b9e9a9381168a9f5cefa5716d 100644
--- a/src/crankshaft/x64/lithium-x64.h
+++ b/src/crankshaft/x64/lithium-x64.h
@@ -35,7 +35,6 @@ class LCodeGen;
   V(CallFunction)                            \
   V(CallNewArray)                            \
   V(CallRuntime)                             \
-  V(CallStub)                                \
   V(CheckArrayBufferNotNeutered)             \
   V(CheckInstanceType)                       \
   V(CheckMaps)                               \
@@ -462,19 +461,6 @@ class LParameter final : public LTemplateInstruction<1, 0, 0> {
 };
 
 
-class LCallStub final : public LTemplateInstruction<1, 1, 0> {
- public:
-  explicit LCallStub(LOperand* context) {
-    inputs_[0] = context;
-  }
-
-  LOperand* context() { return inputs_[0]; }
-
-  DECLARE_CONCRETE_INSTRUCTION(CallStub, "call-stub")
-  DECLARE_HYDROGEN_ACCESSOR(CallStub)
-};
-
-
 class LUnknownOSRValue final : public LTemplateInstruction<1, 0, 0> {
  public:
   bool HasInterestingComment(LCodeGen* gen) const override { return false; }