fix barback and polymer build warnings

pkg/pkg.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.
 
 # Don't run any test-like files that show up in packages directories. It
 # shouldn't be necessary to run "pub install" in these packages, but if you do
 # it shouldn't break the tests.
 */packages/*/*: Skip
 */*/packages/*/*: Skip
 */*/*/packages/*/*: Skip
@@ skipping 291 matching lines @@
 
 [ $compiler == dartanalyzer ]
 # pkg issue 13944; Missing inherited member 'Observable._mirror'
 custom_element/test/analyzer_test: fail
 
 [ $compiler == dart2analyzer ]
 # pkg issue 13944; Missing inherited members: 'ListChangeRecord.addedCount' and 'ListChangeRecord.removedCount'
 custom_element/test/analyzer_test: fail
 
 [ $compiler == dartanalyzer || $compiler == dart2analyzer ]
-barback/test/asset_id_test: StaticWarning
-barback/test/asset_set_test: StaticWarning
-barback/test/asset_test: StaticWarning
-barback/test/cancelable_future_test: StaticWarning
-barback/test/mutliset_test: StaticWarning
-barback/test/package_graph/add_remove_transform_test: StaticWarning
-barback/test/package_graph/errors_test: StaticWarning
-barback/test/package_graph/get_all_assets_test: StaticWarning
-barback/test/package_graph/group_test: StaticWarning
-barback/test/package_graph/many_parallel_transformers_test: StaticWarning
-barback/test/package_graph/repetition_test: StaticWarning
-barback/test/package_graph/source_test: StaticWarning
-barback/test/package_graph/transform_test: StaticWarning
-barback/test/stream_pool_test: StaticWarning
-barback/test/stream_replayer_test: StaticWarning
-barback/test/too_many_open_files_test: StaticWarning
-barback/test/transformer_test: StaticWarning
 csslib/test/big_1_test: StaticWarning
 csslib/test/compiler_test: StaticWarning
 csslib/test/declaration_test: StaticWarning
 csslib/test/error_test: StaticWarning
 csslib/test/extend_test: StaticWarning
 csslib/test/mixin_test: StaticWarning
 csslib/test/nested_test: StaticWarning
 csslib/test/selector_test: StaticWarning
 csslib/test/var_test: StaticWarning
 csslib/test/visitor_test: StaticWarning
 docgen/test/single_library_test: StaticWarning
 http_server/test/http_body_test: StaticWarning
 http_server/test/http_multipart_test: StaticWarning
 http_server/test/virtual_directory_test: StaticWarning
 http_server/test/virtual_host_test: StaticWarning
 http/test/client_test: StaticWarning
 http/test/http_test: StaticWarning
 http/test/mock_client_test: StaticWarning
 http/test/multipart_test: StaticWarning
 http/test/request_test: StaticWarning
 http/test/streamed_request_test: StaticWarning
 intl/test/date_time_format_file_even_test: StaticWarning
 intl/test/date_time_format_file_odd_test: StaticWarning
 intl/test/date_time_format_http_request_test: StaticWarning
 intl/test/date_time_format_local_even_test: StaticWarning
 intl/test/date_time_format_local_odd_test: StaticWarning
-observe/test/transform_test: StaticWarning
-polymer/test/build/*: StaticWarning
-polymer/test/build/utils_test: Pass
-scheduled_test/test/descriptor/async_test: StaticWarning
-scheduled_test/test/descriptor/directory_test: StaticWarning
-scheduled_test/test/descriptor/file_test: StaticWarning
-scheduled_test/test/descriptor/nothing_test: StaticWarning
-scheduled_test/test/descriptor/pattern_test: StaticWarning
-scheduled_test/test/scheduled_future_matchers_test: StaticWarning
-scheduled_test/test/scheduled_process_test: StaticWarning
-scheduled_test/test/scheduled_test/abort_test: StaticWarning
-scheduled_test/test/scheduled_test/current_schedule_current_task_test: StaticWarning
-scheduled_test/test/scheduled_test/current_schedule_errors_test: StaticWarning
-scheduled_test/test/scheduled_test/current_schedule_state_test: StaticWarning
-scheduled_test/test/scheduled_test/nested_task_test: StaticWarning
-scheduled_test/test/scheduled_test/on_complete_test: StaticWarning
-scheduled_test/test/scheduled_test/on_exception_test: StaticWarning
-scheduled_test/test/scheduled_test/out_of_band_task_test: StaticWarning
-scheduled_test/test/scheduled_test/set_up_test: StaticWarning
-scheduled_test/test/scheduled_test/signal_error_test: StaticWarning
-scheduled_test/test/scheduled_test/simple_test: StaticWarning
-scheduled_test/test/scheduled_test/task_return_value_test: StaticWarning
-scheduled_test/test/scheduled_test/timeout_test: StaticWarning
-scheduled_test/test/scheduled_test/wrap_async_test: StaticWarning
-scheduled_test/test/scheduled_test/wrap_future_test: StaticWarning
 unittest/test/matchers_test: StaticWarning
 unittest/test/mock_test: StaticWarning
 watcher/test/directory_watcher_test: StaticWarning
 watcher/test/no_subscription_test: StaticWarning
 watcher/test/ready_test: StaticWarning