dart:platform | Remove isWindows, isLinux, isAndroid, isMacOS from dart:platform.

tests/lib/lib.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.
 
 [ $csp ]
 mirrors/delegate_test: RuntimeError # Issue 13864
 
 [ $compiler == dart2js ]
 async/schedule_microtask3_test: RuntimeError # _enqueueImmediate runs after Timer. http://dartbug.com/9002
 async/schedule_microtask4_test: Pass, RuntimeError # no global exception handler in isolates. http://dartbug.com/9012
@@ skipping 113 matching lines @@
 
 
 [ $compiler == dart2js && $browser ]
 async/timer_not_available_test: Fail, OK # only meant to test when there is no way to
                                          # implement timer (currently only in d8)
 
 [ $compiler == dart2dart ]
 mirrors/*: Skip # http://dartbug.com/11511
 async/schedule_microtask6_test: Fail             # Issue 10957 - may be related to issue 10910
 async/schedule_microtask3_test: RuntimeError # Issue 13719: Please triage this failure.
+platform/package_root_test: Fail # Issue 14451
+platform/script_test: Fail # Issue 14451
+platform/isolate_test: Fail # Issue 14451
+
 
 [ $compiler == dart2dart && $minified ]
 json/json_test: Fail                            # Issue 10961
 
 [ $compiler == dart2js && $minified ]
 mirrors/typedef_test/01: Fail # http://dartbug.com/6490
 
 [ $runtime == ff ]
 # FF setTimeout can fire early: https://bugzilla.mozilla.org/show_bug.cgi?id=291386
 async/multiple_timer_test: Pass, Fail
@@ skipping 90 matching lines @@
 mirrors/redirecting_factory_test/none: Fail # Issue 14285
 mirrors/type_variable_owner_test/none: Fail # Issue 14356
 
 [ $compiler == none && $runtime == dartium ]
 async/schedule_microtask5_test: Pass, Timeout # Issue 13719: Please triage this failure.
 async/timer_cancel2_test: Pass, Timeout # Issue 13719: Please triage this failure.
 
 [ ($compiler != none && $runtime != none) || ($compiler == none && ($runtime != dartium && $runtime != drt)) ]
 async/schedule_microtask_test: Fail # Issue 9001, Issue 9002