Track usage of "this" and "arguments" in Scope

src/globals.h

Index: src/globals.h
diff --git a/src/globals.h b/src/globals.h
index bef22cff13ee4c2ecadd78ee1c5e9695d2e083b9..0e6fcae9d7480deab1be7ea35a2132e3aaa04bf7 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -648,7 +648,8 @@ enum ScopeType {
   GLOBAL_SCOPE,    // The top-level scope for a program or a top-level eval.
   CATCH_SCOPE,     // The scope introduced by catch.
   BLOCK_SCOPE,     // The scope introduced by a new block.
-  WITH_SCOPE       // The scope introduced by with.
+  WITH_SCOPE,      // The scope introduced by with.
+  ARROW_SCOPE      // The top-level scope for an arrow function literal.
 };