[turbofan] Drop the obsolete TypeGuard operator.

src/compiler/js-intrinsic-lowering.h

 // Copyright 2015 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_COMPILER_JS_INTRINSIC_LOWERING_H_
 #define V8_COMPILER_JS_INTRINSIC_LOWERING_H_
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph-reducer.h"
 
@@ skipping 21 matching lines @@
 
   JSIntrinsicLowering(Editor* editor, JSGraph* jsgraph,
                       DeoptimizationMode mode);
   ~JSIntrinsicLowering() final {}
 
   Reduction Reduce(Node* node) final;
 
  private:
   Reduction ReduceCreateIterResultObject(Node* node);
   Reduction ReduceDeoptimizeNow(Node* node);
-  Reduction ReduceDoubleHi(Node* node);
-  Reduction ReduceDoubleLo(Node* node);
   Reduction ReduceGeneratorClose(Node* node);
   Reduction ReduceGeneratorGetInputOrDebugPos(Node* node);
   Reduction ReduceGeneratorGetResumeMode(Node* node);
   Reduction ReduceIsInstanceType(Node* node, InstanceType instance_type);
   Reduction ReduceIsJSReceiver(Node* node);
   Reduction ReduceIsSmi(Node* node);
   Reduction ReduceValueOf(Node* node);
   Reduction ReduceFixedArrayGet(Node* node);
   Reduction ReduceFixedArraySet(Node* node);
   Reduction ReduceRegExpConstructResult(Node* node);
@@ skipping 31 matching lines @@
 
   JSGraph* const jsgraph_;
   DeoptimizationMode const mode_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_JS_INTRINSIC_LOWERING_H_