[turbofan] Fix context chain extension for top-level code.

src/compiler/ast-graph-builder.h

 // Copyright 2014 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_AST_GRAPH_BUILDER_H_
 #define V8_COMPILER_AST_GRAPH_BUILDER_H_
 
 #include "src/ast.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/liveness-analyzer.h"
@@ skipping 127 matching lines @@
   void set_execution_control(ControlScope* ctrl) { execution_control_ = ctrl; }
   void set_execution_context(ContextScope* ctx) { execution_context_ = ctx; }
 
   // Create the main graph body by visiting the AST.
   void CreateGraphBody(bool stack_check);
 
   // Create the node that represents the outer context of the function.
   void CreateFunctionContext(bool constant_context);
 
   // Get or create the node that represents the outer function closure.
+  Node* GetFunctionClosureForContext();
   Node* GetFunctionClosure();
 
   // Node creation helpers.
   Node* NewNode(const Operator* op, bool incomplete = false) {
     return MakeNode(op, 0, static_cast<Node**>(NULL), incomplete);
   }
 
   Node* NewNode(const Operator* op, Node* n1) {
     return MakeNode(op, 1, &n1, false);
   }
@@ skipping 368 matching lines @@
 
   // Prepare environment to be used as loop header.
   void PrepareForLoop(BitVector* assigned, bool is_osr = false);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_AST_GRAPH_BUILDER_H_