[turbofan] Rip out the unused OsrGuard node.

src/compiler/js-frame-specialization.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_FRAME_SPECIALIZATION_H_
 #define V8_COMPILER_JS_FRAME_SPECIALIZATION_H_
 
 #include "src/compiler/graph-reducer.h"
 
 namespace v8 {
@@ skipping 11 matching lines @@
  public:
   JSFrameSpecialization(Editor* editor, JavaScriptFrame const* frame,
                         JSGraph* jsgraph)
       : AdvancedReducer(editor), frame_(frame), jsgraph_(jsgraph) {}
   ~JSFrameSpecialization() final {}
 
   Reduction Reduce(Node* node) final;
 
  private:
   Reduction ReduceOsrValue(Node* node);
-  Reduction ReduceOsrGuard(Node* node);
   Reduction ReduceParameter(Node* node);
 
   Isolate* isolate() const;
   JavaScriptFrame const* frame() const { return frame_; }
   JSGraph* jsgraph() const { return jsgraph_; }
 
   JavaScriptFrame const* const frame_;
   JSGraph* const jsgraph_;
 
   DISALLOW_COPY_AND_ASSIGN(JSFrameSpecialization);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_JS_FRAME_SPECIALIZATION_H_