Implement proper scoping for "this" in arrow functions

src/preparser.h

Index: src/preparser.h
diff --git a/src/preparser.h b/src/preparser.h
index e2929b827d238d120528f2393a0160b1b3c4aaa0..fabb5074772aeee7b10f7f3b43a222666340603a 100644
--- a/src/preparser.h
+++ b/src/preparser.h
@@ -1019,7 +1019,6 @@ class PreParserScope {
   void RecordArgumentsUsage() {}
   void RecordSuperPropertyUsage() {}
   void RecordSuperConstructorCallUsage() {}
-  void RecordThisUsage() {}
 
   // Allow scope->Foo() to work.
   PreParserScope* operator->() { return this; }
@@ -1855,7 +1854,6 @@ ParserBase<Traits>::ParsePrimaryExpression(bool* ok) {
   switch (token) {
     case Token::THIS: {
       Consume(Token::THIS);
-      scope_->RecordThisUsage();
       result = this->ThisExpression(scope_, factory());
       break;
     }