Do not allow keyword on containers without pos args

Author: José Valim

lib/elixir/src/elixir_parser.yrl

@@ -411,7 +411,6 @@ container_expr -> no_parens_expr : throw_no_parens_many_strict('$1').
 container_args_base -> container_expr : ['$1'].
 container_args_base -> container_args_base ',' container_expr : ['$3'|'$1'].
 
-container_args -> kw : ['$1'].
 container_args -> container_args_base : lists:reverse('$1').
 container_args -> container_args_base ',' : lists:reverse('$1').
 container_args -> container_args_base ',' kw : lists:reverse(['$3'|'$1']).

lib/elixir/test/elixir/tuple_test.exs

@@ -13,7 +13,6 @@ defmodule TupleTest do
 
   test :keywords do
     assert {1, 2, three: :four} == {1, 2, [three: :four]}
-    assert {one: :two} == {[one: :two]}
   end
 
   test :optional_comma do