[es6] Fix missing bits for full @@toPrimitive support.

src/contexts.h

Index: src/contexts.h
diff --git a/src/contexts.h b/src/contexts.h
index 9739c721b39aafd9f0023ed270779c49a3c1ee9e..84829f527efb42e2dd7805d7ca9c74e7e938bb30 100644
--- a/src/contexts.h
+++ b/src/contexts.h
@@ -78,12 +78,10 @@ enum BindingFlags {
   V(GET_TEMPLATE_CALL_SITE_INDEX, JSFunction, get_template_call_site)     \
   V(MAKE_RANGE_ERROR_INDEX, JSFunction, make_range_error)                 \
   V(MAKE_TYPE_ERROR_INDEX, JSFunction, make_type_error)                   \
-  V(NON_NUMBER_TO_NUMBER_INDEX, JSFunction, non_number_to_number)         \
   V(REFLECT_APPLY_INDEX, JSFunction, reflect_apply)                       \
   V(REFLECT_CONSTRUCT_INDEX, JSFunction, reflect_construct)               \
   V(SPREAD_ARGUMENTS_INDEX, JSFunction, spread_arguments)                 \
-  V(SPREAD_ITERABLE_INDEX, JSFunction, spread_iterable)                   \
-  V(TO_NUMBER_FUN_INDEX, JSFunction, to_number_fun)
+  V(SPREAD_ITERABLE_INDEX, JSFunction, spread_iterable)
 
 
 #define NATIVE_CONTEXT_JS_BUILTINS(V)                                 \