Disable ES6 tail call elimination for native functions.

src/parsing/parser-base.h

Index: src/parsing/parser-base.h
diff --git a/src/parsing/parser-base.h b/src/parsing/parser-base.h
index ef492e0c01ad1df71767b8bbf06334d7f9ee2900..5014a747557b49fcd2dd9cc218c00dab48b2e4db 100644
--- a/src/parsing/parser-base.h
+++ b/src/parsing/parser-base.h
@@ -108,6 +108,7 @@ class ParserBase : public Traits {
         stack_overflow_(false),
         allow_lazy_(false),
         allow_natives_(false),
+        allow_tailcalls_(false),
         allow_harmony_sloppy_(false),
         allow_harmony_sloppy_function_(false),
         allow_harmony_sloppy_let_(false),
@@ -129,6 +130,7 @@ class ParserBase : public Traits {
 
   ALLOW_ACCESSORS(lazy);
   ALLOW_ACCESSORS(natives);
+  ALLOW_ACCESSORS(tailcalls);
   ALLOW_ACCESSORS(harmony_sloppy);
   ALLOW_ACCESSORS(harmony_sloppy_function);
   ALLOW_ACCESSORS(harmony_sloppy_let);
@@ -918,6 +920,7 @@ class ParserBase : public Traits {
 
   bool allow_lazy_;
   bool allow_natives_;
+  bool allow_tailcalls_;
   bool allow_harmony_sloppy_;
   bool allow_harmony_sloppy_function_;
   bool allow_harmony_sloppy_let_;