Issue 6971. Don't report error for using built-in identifier as part of parameterized type.

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.
@@ skipping 69 matching lines @@
 compile_time_constant_checked3_test/02: Fail, OK
 compile_time_constant_checked3_test/03: Fail, OK
 compile_time_constant_checked3_test/04: Fail, OK
 compile_time_constant_checked3_test/05: Fail, OK
 compile_time_constant_checked3_test/06: Fail, OK
 
 [ $compiler == none && $checked ]
 default_factory2_test/01: Fail # Issue 7075.
 
 [ $compiler == dartc ]
-built_in_identifier_prefix_test: Fail # http://dartbug.com/6971
 library_juxtaposition_test: Fail # Issue 6881
 new_expression_type_args_test/0*: Fail # Wrongly reports compile-time error.
 redirecting_factory_infinite_steps_test/01: Fail # http://dartbug.com/6560
 implicit_this_test/none: Fail # should not warn about allocating SubAbstract2
 metadata_test: Fail
 bad_override_test/01: Fail, OK # issue 6578, warning expected on "static" modifier
 bad_override_test/02: Fail, OK # issue 6578, warning expected on "static" modifier
 const_locals_test: Fail
 const_nested_test: Fail
 application_negative_test: Fail # Runtime only test, rewrite as multitest
@@ skipping 429 matching lines @@
 
 # This is a VM error when the compiled code is run.
 invocation_mirror_test: Fail # issue 3326.
 invocation_mirror_indirect_test: Fail # issue 3326.
 super_call4_test: Fail # issue 3326.
 
 [ $compiler == dart2dart && $minified ]
 import_core_prefix_test: Pass
 prefix22_test: Pass
 invocation_mirror2_test: Fail