[intrinsics] Remove %_IsFunction inline intrinsic.

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 28 matching lines @@
 
  private:
   Reduction ReduceConstructDouble(Node* node);
   Reduction ReduceCreateIterResultObject(Node* node);
   Reduction ReduceDeoptimizeNow(Node* node);
   Reduction ReduceDoubleHi(Node* node);
   Reduction ReduceDoubleLo(Node* node);
   Reduction ReduceIncrementStatsCounter(Node* node);
   Reduction ReduceIsMinusZero(Node* node);
   Reduction ReduceIsInstanceType(Node* node, InstanceType instance_type);
-  Reduction ReduceIsFunction(Node* node);
   Reduction ReduceIsJSReceiver(Node* node);
   Reduction ReduceIsSmi(Node* node);
   Reduction ReduceJSValueGetValue(Node* node);
   Reduction ReduceMathClz32(Node* node);
   Reduction ReduceMathFloor(Node* node);
   Reduction ReduceMathSqrt(Node* node);
   Reduction ReduceValueOf(Node* node);
   Reduction ReduceFixedArrayGet(Node* node);
   Reduction ReduceFixedArraySet(Node* node);
   Reduction ReduceRegExpConstructResult(Node* node);
@@ skipping 34 matching lines @@
   JSGraph* const jsgraph_;
   DeoptimizationMode const mode_;
   TypeCache const& type_cache_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_JS_INTRINSIC_LOWERING_H_