Improve and simplify removal of unreachable code

src/hydrogen-deoptimizing-mark.h

Index: src/hydrogen-deoptimizing-mark.h
diff --git a/src/hydrogen-deoptimizing-mark.h b/src/hydrogen-deoptimizing-mark.h
deleted file mode 100644
index 7d6e6e4bda3020cc9d3118060e0723054f17f9a6..0000000000000000000000000000000000000000
--- a/src/hydrogen-deoptimizing-mark.h
+++ /dev/null
@@ -1,56 +0,0 @@
-// Copyright 2013 the V8 project authors. All rights reserved.
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-//       notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-//       copyright notice, this list of conditions and the following
-//       disclaimer in the documentation and/or other materials provided
-//       with the distribution.
-//     * Neither the name of Google Inc. nor the names of its
-//       contributors may be used to endorse or promote products derived
-//       from this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-#ifndef V8_HYDROGEN_DEOPTIMIZING_MARK_H_
-#define V8_HYDROGEN_DEOPTIMIZING_MARK_H_
-
-#include "hydrogen.h"
-
-namespace v8 {
-namespace internal {
-
-
-// Mark all blocks that are dominated by an unconditional soft deoptimize to
-// prevent code motion across those blocks.
-class HPropagateDeoptimizingMarkPhase : public HPhase {
- public:
-  explicit HPropagateDeoptimizingMarkPhase(HGraph* graph)
-      : HPhase("H_Propagate deoptimizing mark", graph) { }
-
-  void Run();
-
- private:
-  void MarkAsDeoptimizing();
-  void NullifyUnreachableInstructions();
-
-  DISALLOW_COPY_AND_ASSIGN(HPropagateDeoptimizingMarkPhase);
-};
-
-
-} }  // namespace v8::internal
-
-#endif  // V8_HYDROGEN_DEOPTIMIZING_MARK_H_