[Interpreter] Add support for VisitThisFunction.

src/interpreter/bytecode-generator.cc

 // Copyright 2015 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.
 
 #include "src/interpreter/bytecode-generator.h"
 
 #include "src/compiler.h"
 #include "src/interpreter/control-flow-builders.h"
 #include "src/objects.h"
 #include "src/parser.h"
@@ skipping 1851 matching lines @@
 
 void BytecodeGenerator::VisitSpread(Spread* expr) { UNREACHABLE(); }
 
 
 void BytecodeGenerator::VisitEmptyParentheses(EmptyParentheses* expr) {
   UNREACHABLE();
 }
 
 
 void BytecodeGenerator::VisitThisFunction(ThisFunction* expr) {
-  UNIMPLEMENTED();
+  execution_result()->SetResultInRegister(Register::function_closure());
 }
 
 
 void BytecodeGenerator::VisitSuperCallReference(SuperCallReference* expr) {
   UNIMPLEMENTED();
 }
 
 
 void BytecodeGenerator::VisitSuperPropertyReference(
     SuperPropertyReference* expr) {
@@ skipping 280 matching lines @@
 }
 
 
 int BytecodeGenerator::feedback_index(FeedbackVectorSlot slot) const {
   return info()->feedback_vector()->GetIndex(slot);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8