Implement proper scoping for "this" in arrow functions

src/ast.cc

 // 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.
 
 #include "src/ast.h"
 
 #include <cmath>  // For isfinite.
 #include "src/builtins.h"
 #include "src/code-stubs.h"
 #include "src/contexts.h"
@@ skipping 53 matching lines @@
       bit_field_(IsThisField::encode(var->is_this()) |
                  IsAssignedField::encode(false) |
                  IsResolvedField::encode(false)),
       variable_feedback_slot_(FeedbackVectorICSlot::Invalid()),
       raw_name_(var->raw_name()),
       interface_(var->interface()) {
   BindTo(var);
 }
 
 
-VariableProxy::VariableProxy(Zone* zone, const AstRawString* name, bool is_this,
-                             Interface* interface, int position)
+VariableProxy::VariableProxy(Zone* zone,
+                             const AstRawString* name,
+                             Variable::Kind variable_kind,
+                             Interface* interface,
+                             int position)
     : Expression(zone, position),
-      bit_field_(IsThisField::encode(is_this) | IsAssignedField::encode(false) |
+      bit_field_(IsThisField::encode(variable_kind == Variable::THIS) |
+                 IsAssignedField::encode(false) |
                  IsResolvedField::encode(false)),
       variable_feedback_slot_(FeedbackVectorICSlot::Invalid()),
       raw_name_(name),
       interface_(interface) {}
 
 
 void VariableProxy::BindTo(Variable* var) {
   DCHECK(!FLAG_harmony_modules || interface_->IsUnified(var->interface()));
   DCHECK((is_this() && var->is_this()) || raw_name() == var->raw_name());
   // Ideally CONST-ness should match. However, this is very hard to achieve
@@ skipping 941 matching lines @@
 // static
 bool Literal::Match(void* literal1, void* literal2) {
   const AstValue* x = static_cast<Literal*>(literal1)->raw_value();
   const AstValue* y = static_cast<Literal*>(literal2)->raw_value();
   return (x->IsString() && y->IsString() && *x->AsString() == *y->AsString()) ||
          (x->IsNumber() && y->IsNumber() && x->AsNumber() == y->AsNumber());
 }
 
 
 } }  // namespace v8::internal