[compiler] Make OptimizedCompileJob agnostic from backend.

src/crankshaft/lithium-codegen.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_CRANKSHAFT_LITHIUM_CODEGEN_H_
 #define V8_CRANKSHAFT_LITHIUM_CODEGEN_H_
 
 #include "src/bailout-reason.h"
 #include "src/compiler.h"
 #include "src/deoptimizer.h"
 
 namespace v8 {
 namespace internal {
 
+class HGraph;
+class LChunk;
 class LEnvironment;
 class LInstruction;
 class LPlatformChunk;
 
 class LCodeGenBase BASE_EMBEDDED {
  public:
   LCodeGenBase(LChunk* chunk,
                MacroAssembler* assembler,
                CompilationInfo* info);
   virtual ~LCodeGenBase() {}
@@ skipping 70 matching lines @@
   // Methods for code dependencies.
   void AddDeprecationDependency(Handle<Map> map);
   void AddStabilityDependency(Handle<Map> map);
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CRANKSHAFT_LITHIUM_CODEGEN_H_