Issue 14388. Remove implicit setters for final fields.

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 272 matching lines @@
 unittest/test/missing_tick_test: Fail, OK # This test should fail, not time out.
 
 # Issue http://dartbug.com/12930
 [ $runtime == vm ]
 intl/test/message_extraction/message_extraction_test: Pass, Fail # Issue 12930
 
 [ $compiler == none && $runtime == dartium ]
 source_maps/test/parser_test: Pass, Timeout # Issue 13719: Please triage this failure.
 
 [ $compiler == dartanalyzer ]
-# pkg issue 13944; Missing inherited members: 'ListChangeRecord.addedCount' and 'ListChangeRecord.removedCount'
+# pkg issue 13944; Missing inherited member 'Observable._mirror'
 custom_element/test/analyzer_test: fail
 template_binding/test/analyzer_test: fail
 observe/test/observe_test: fail
 
-# pkg issue 13945; Missing inherited member 'Trace.frames'
-observe/test/observe_test: fail
-
 [ $compiler == dart2analyzer ]
 # pkg issue 13944; Missing inherited members: 'ListChangeRecord.addedCount' and 'ListChangeRecord.removedCount'
 custom_element/test/analyzer_test: fail
 template_binding/test/analyzer_test: fail
 observe/test/observe_test: fail
 
 # pkg issue 13945; Missing inherited member 'Trace.frames'
 observe/test/observe_test: fail