[turbofan] Remove outdated forward declarations.

src/compiler/schedule.h

 // Copyright 2013 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_SCHEDULE_H_
 #define V8_COMPILER_SCHEDULE_H_
 
 #include <iosfwd>
 
 #include "src/zone-containers.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Forward declarations.
 class BasicBlock;
 class BasicBlockInstrumentor;
-class CodeGenerator;  // Because of a namespace bug in clang.
-class ConstructScheduleData;
 class Node;
 
 
 typedef ZoneVector<BasicBlock*> BasicBlockVector;
 typedef ZoneVector<Node*> NodeVector;
 
 
 // A basic block contains an ordered list of nodes and ends with a control
 // node. Note that if a basic block has phis, then all phis must appear as the
 // first nodes in the block.
@@ skipping 243 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(Schedule);
 };
 
 std::ostream& operator<<(std::ostream&, const Schedule&);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SCHEDULE_H_