[turbofan] Make pipeline.h independent of compiler.h.

src/compiler/pipeline.h

Index: src/compiler/pipeline.h
diff --git a/src/compiler/pipeline.h b/src/compiler/pipeline.h
index 42b1954691665f5807362ae8ba21d6cad7422958..edb8191862141604e5d0a6d52fa7eff23173c003 100644
--- a/src/compiler/pipeline.h
+++ b/src/compiler/pipeline.h
@@ -7,11 +7,12 @@
 
 // Clients of this interface shouldn't depend on lots of compiler internals.
 // Do not include anything from src/compiler here!
-#include "src/compiler.h"
+#include "src/objects.h"
 
 namespace v8 {
 namespace internal {
 
+class CompilationInfo;
 class RegisterConfiguration;
 
 namespace compiler {
@@ -57,9 +58,6 @@ class Pipeline {
                                              Schedule* schedule = nullptr);
 
  private:
-  CompilationInfo* info_;
-  PipelineData* data_;
-
   // Helpers for executing pipeline phases.
   template <typename Phase>
   void Run();
@@ -68,14 +66,19 @@ class Pipeline {
   template <typename Phase, typename Arg0, typename Arg1>
   void Run(Arg0 arg_0, Arg1 arg_1);
 
-  CompilationInfo* info() const { return info_; }
-  Isolate* isolate() { return info_->isolate(); }
-
   void BeginPhaseKind(const char* phase_kind);
   void RunPrintAndVerify(const char* phase, bool untyped = false);
   Handle<Code> ScheduleAndGenerateCode(CallDescriptor* call_descriptor);
   void AllocateRegisters(const RegisterConfiguration* config,
                          CallDescriptor* descriptor, bool run_verifier);
+
+  CompilationInfo* info() const { return info_; }
+  Isolate* isolate() const;
+
+  CompilationInfo* const info_;
+  PipelineData* data_;
+
+  DISALLOW_COPY_AND_ASSIGN(Pipeline);
 };
 
 }  // namespace compiler