[turbofan] refactor pipeline to use hydrogen like Run calls

src/compiler/ast-graph-builder.h

Index: src/compiler/ast-graph-builder.h
diff --git a/src/compiler/ast-graph-builder.h b/src/compiler/ast-graph-builder.h
index d076b5a110b52cded26a59663110468085f33dda..dfa4b93e59a5d4c944a8323d555e21bd3f235017 100644
--- a/src/compiler/ast-graph-builder.h
+++ b/src/compiler/ast-graph-builder.h
@@ -58,10 +58,6 @@ class AstGraphBuilder : public StructuredGraphBuilder, public AstVisitor {
   typedef StructuredGraphBuilder::Environment BaseEnvironment;
   virtual BaseEnvironment* CopyEnvironment(BaseEnvironment* env) OVERRIDE;
 
-  // TODO(mstarzinger): The pipeline only needs to be a friend to access the
-  // function context. Remove as soon as the context is a parameter.
-  friend class Pipeline;
-
   // Getters for values in the activation record.
   Node* GetFunctionClosure();
   Node* GetFunctionContext();