Remove old code generator.

runtime/vm/opt_code_generator_x64.h

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-#ifndef VM_OPT_CODE_GENERATOR_X64_H_
-#define VM_OPT_CODE_GENERATOR_X64_H_
-
-#ifndef VM_OPT_CODE_GENERATOR_H_
-#error Do not include opt_code_generator_x64.h; use opt_code_generator.h.
-#endif
-
-#include "vm/code_generator.h"
-
-namespace dart {
-
-// Temporary hierarchy, until optimized code generator implemented.
-class OptimizingCodeGenerator : public CodeGenerator {
- public:
-  OptimizingCodeGenerator(Assembler* assembler,
-                          const ParsedFunction& parsed_function)
-      : CodeGenerator(assembler, parsed_function) {}
-
-  virtual bool IsOptimizing() const {
-    return true;
-  }
-
- private:
-  DISALLOW_IMPLICIT_CONSTRUCTORS(OptimizingCodeGenerator);
-};
-
-}  // namespace dart
-
-
-#endif  // VM_OPT_CODE_GENERATOR_X64_H_