[turbofan] Call FastNewContextStub for function context.

src/code-factory.h

 // Copyright 2012 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_CODE_FACTORY_H_
 #define V8_CODE_FACTORY_H_
 
 #include "src/allocation.h"
 #include "src/assembler.h"
 #include "src/codegen.h"
@@ skipping 67 matching lines @@
 
   static Callable StringAdd(Isolate* isolate, StringAddFlags flags,
                             PretenureFlag pretenure_flag);
   static Callable StringCompare(Isolate* isolate);
 
   static Callable Typeof(Isolate* isolate);
 
   static Callable FastCloneShallowArray(Isolate* isolate);
   static Callable FastCloneShallowObject(Isolate* isolate, int length);
 
+  static Callable FastNewContext(Isolate* isolate, int slot_count);
   static Callable FastNewClosure(Isolate* isolate, LanguageMode language_mode,
                                  FunctionKind kind);
 
   static Callable ArgumentsAccess(Isolate* isolate, bool is_unmapped_arguments,
                                   bool has_duplicate_parameters);
 
   static Callable AllocateHeapNumber(Isolate* isolate);
 
   static Callable CallFunction(Isolate* isolate, int argc,
                                CallFunctionFlags flags);
 
   static Callable PushArgsAndCall(Isolate* isolate);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CODE_FACTORY_H_