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

sdk/lib/platform/platform.dart

 // Copyright (c) 2013, 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.
 
 /**
  * Runtime information about the current platform.
  */
 library dart.platform;
 
 /**
  * The number of processors of the platform.
  *
  * Returns null if no information is available.
  *
  * Supported on the standalone Dart executable.
  */
 external int get numberOfProcessors;
 
 /**
  * The path separator used on the platform to separate
  * components in file paths.
+ *
+ * Returns null if the path separator is unknown or not valid.
+ *
+ * Supported on the standalone Dart executable and on dart2js.
  */
 external String get pathSeparator;
 
 /**
  * A string (`linux`, `macos`, `windows` or `android`)
  * representing the operating system.
  *
  * Returns null if the operating system could not be determined.
  */
 external String get operatingSystem;
@@ skipping 10 matching lines @@
 /**
  * The version of the current Dart runtime.
  *
  * Returns null if not running a Dart runtime.
  *
  * Supported on the standalone Dart executable.
  */
 external String get version;
 
 /**
- * True if the operating system is Linux.
- */
-// TODO(6997): Replace with bool get isLinux => operatingSystem == 'linux'
-// when issue with patched top-level functions is fixed.
-external bool get isLinux;
-
-/**
- * True if the operating system is Mac OS.
- */
-external bool get isMacOS;
-
-/**
- * True if the operating system is Windows.
- */
-external bool get isWindows;
-
-/**
- * True if the operating system is Android.
- */
-external bool get isAndroid;
-
-/**
  * The environment for this instance of the platform.
  *
  * If environment variables are not supported on this platform, or not
  * available, null is returned.
  *
  * Environment variables on Windows are case-insensitive. The map
  * returned on Windows is therefore case-insensitive and converts
  * all keys and key arguments to its methods to upper case.
  * On other platforms the returned map is
  * a standard case-sensitive map.
@@ skipping 41 matching lines @@
  * used to run the script in this isolate.  This is the directory in which
  * Dart packages are looked up.
  *
  * If there is no --package-root flag, then the empty string is returned.
  *
  * Returns null if the information is not available on this platform.
  *
  * Supported on the standalone Dart executable.
  */
 external String get packageRoot;