Implement proper scoping for "this" in arrow functions

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"
 
@@ skipping 330 matching lines @@
   int parameters_count() const { return parameters_count_; }
   int locals_count() const { return locals_count_; }
   int stack_height() {
     return static_cast<int>(values()->size()) - parameters_count_ -
            locals_count_;
   }
 
   // Operations on parameter or local variables. The parameter indices are
   // shifted by 1 (receiver is parameter index -1 but environment index 0).
   void Bind(Variable* variable, Node* node) {
-    DCHECK(variable->IsStackAllocated());
-    if (variable->IsParameter()) {
-      values()->at(variable->index() + 1) = node;
+    if (variable->is_this()) {
+      values()->at(0) = node;
     } else {
-      DCHECK(variable->IsStackLocal());
-      values()->at(variable->index() + parameters_count_) = node;
+      DCHECK(variable->IsStackAllocated());
+      if (variable->IsParameter()) {
+        values()->at(variable->index() + 1) = node;
+      } else {
+        DCHECK(variable->IsStackLocal());
+        values()->at(variable->index() + parameters_count_) = node;
+      }
     }
   }
   Node* Lookup(Variable* variable) {
-    DCHECK(variable->IsStackAllocated());
-    if (variable->IsParameter()) {
-      return values()->at(variable->index() + 1);
+    if (variable->is_this()) {
+      return values()->at(0);
     } else {
-      DCHECK(variable->IsStackLocal());
-      return values()->at(variable->index() + parameters_count_);
+      DCHECK(variable->IsStackAllocated());
+      if (variable->IsParameter()) {
+        return values()->at(variable->index() + 1);
+      } else {
+        DCHECK(variable->IsStackLocal());
+        return values()->at(variable->index() + parameters_count_);
+      }
     }
   }
 
   Node* Context() const { return contexts_.back(); }
   void PushContext(Node* context) { contexts()->push_back(context); }
   void PopContext() { contexts()->pop_back(); }
 
   // Operations on the operand stack.
   void Push(Node* node) {
     values()->push_back(node);
@@ skipping 99 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_