[turbofan] Use builtin inlining mechanism for Math.floor.

src/compiler/js-builtin-reducer.h

 // Copyright 2014 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_BUILTIN_REDUCER_H_
 #define V8_COMPILER_JS_BUILTIN_REDUCER_H_
 
 #include "src/compiler/graph-reducer.h"
 #include "src/compiler/simplified-operator.h"
 
@@ skipping 13 matching lines @@
   ~JSBuiltinReducer() FINAL {}
 
   Reduction Reduce(Node* node) FINAL;
 
  private:
   Reduction ReduceMathAbs(Node* node);
   Reduction ReduceMathSqrt(Node* node);
   Reduction ReduceMathMax(Node* node);
   Reduction ReduceMathImul(Node* node);
   Reduction ReduceMathFround(Node* node);
-  Reduction ReduceMathFloor(Node* node);
 
   JSGraph* jsgraph() const { return jsgraph_; }
   Graph* graph() const;
   CommonOperatorBuilder* common() const;
   MachineOperatorBuilder* machine() const;
   SimplifiedOperatorBuilder* simplified() { return &simplified_; }
 
   JSGraph* jsgraph_;
   SimplifiedOperatorBuilder simplified_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_JS_BUILTIN_REDUCER_H_