Fix generic mixins (issue 11803).

tests/language/language.status

 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 # This directory contains tests that are intended to show the
 # current state of the language.
 
 # In order to maintain maximum test coverage for all builds,
 # please use the following procedure to mark a test
 # failed on architectures other than the one you are working on.
 #
 # 1) Copy the old version of the test to
 #    tests/language/src/test_name_[dartc|vm]_test.dart.
 #    to maintain coverage.
 # 2) File a bug on each architecture for the failure due to the language change.
 # 3) Update the language/src directory with the updated test.
 
 [ $compiler == dart2dart ]
-mixin_type_parameters_simple_test: Fail, Crash # issue 11803
 mixin_super_constructor_named_test: Fail
 mixin_super_constructor_positionals_test: Fail
 const_constructor_super_test/01: fail
 
 [ $compiler == none ]
-mixin_type_parameters_simple_test: Fail, Crash # issue 11803
 mixin_super_constructor_named_test: Fail
 mixin_super_constructor_positionals_test: Fail
 built_in_identifier_prefix_test: Fail # http://dartbug.com/6970
 library_juxtaposition_test: Fail # Issue 6877
 pseudo_kw_illegal_test/14: Fail  # Issue 356
 bound_closure_equality_test: Fail # Issue 10849
 
 # These bugs refer currently ongoing language discussions.
 constructor5_test: Fail           # (Discussion ongoing)
 
@@ skipping 277 matching lines @@
 try_catch4_test: Crash, Fail
 
 
 [ $arch == mips ]
 *: Skip
 
 [ $arch == simmips ]
 arithmetic_test: Crash  # Too far relative branch.
 large_implicit_getter_test: Crash  # Too far relative branch.
 try_catch4_test: Fail