[stubs] Port LoadScriptContextFieldStub and StoreScriptContextFieldStub to TurboFan.

src/code-stub-assembler.h

 // Copyright 2016 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_STUB_ASSEMBLER_H_
 #define V8_CODE_STUB_ASSEMBLER_H_
 
 #include <functional>
 
 #include "src/compiler/code-assembler.h"
@@ skipping 256 matching lines @@
       Label* if_hole = nullptr);
 
   // Load Float64 value by |base| + |offset| address. If the value is a double
   // hole then jump to |if_hole|. If |machine_type| is None then only the hole
   // check is generated.
   compiler::Node* LoadDoubleWithHoleCheck(
       compiler::Node* base, compiler::Node* offset, Label* if_hole,
       MachineType machine_type = MachineType::Float64());
 
   // Context manipulation
+  compiler::Node* LoadContextElement(compiler::Node* context, int slot_index);
   compiler::Node* LoadNativeContext(compiler::Node* context);
 
   compiler::Node* LoadJSArrayElementsMap(ElementsKind kind,
                                          compiler::Node* native_context);
 
   // Store the floating point value of a HeapNumber.
   compiler::Node* StoreHeapNumberValue(compiler::Node* object,
                                        compiler::Node* value);
   // Store a field to an object on the heap.
   compiler::Node* StoreObjectField(
@@ skipping 364 matching lines @@
     return EmitKeyedSloppyArguments(receiver, key, nullptr, bailout);
   }
 
   // Emits keyed sloppy arguments store.
   void StoreKeyedSloppyArguments(compiler::Node* receiver, compiler::Node* key,
                                  compiler::Node* value, Label* bailout) {
     DCHECK_NOT_NULL(value);
     EmitKeyedSloppyArguments(receiver, key, value, bailout);
   }
 
+  // Loads script context from the script context table.
+  compiler::Node* LoadScriptContext(compiler::Node* context, int context_index);
+
   void LoadIC(const LoadICParameters* p);
   void LoadGlobalIC(const LoadICParameters* p);
   void KeyedLoadIC(const LoadICParameters* p);
   void KeyedLoadICGeneric(const LoadICParameters* p);
 
   // Get the enumerable length from |map| and return the result as a Smi.
   compiler::Node* EnumLength(compiler::Node* map);
 
   // Check the cache validity for |receiver|. Branch to |use_cache| if
   // the cache is valid, otherwise branch to |use_runtime|.
@@ skipping 59 matching lines @@
                                            Label* bailout);
 
   static const int kElementLoopUnrollThreshold = 8;
 };
 
 DEFINE_OPERATORS_FOR_FLAGS(CodeStubAssembler::AllocationFlags);
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_CODE_STUB_ASSEMBLER_H_