Report iOS as iOS rather than OS X.

sdk/lib/io/platform.dart

Index: sdk/lib/io/platform.dart
diff --git a/sdk/lib/io/platform.dart b/sdk/lib/io/platform.dart
index 56ddea0193b0df98b43e703e0c98828f4eb1e696..c9e1cc66d6d084212d356c0be7a099731327d3ce 100644
--- a/sdk/lib/io/platform.dart
+++ b/sdk/lib/io/platform.dart
@@ -84,7 +84,7 @@ class Platform {
   static String get pathSeparator => _pathSeparator;
 
   /**
-   * Get a string (`linux`, `macos`, `windows` or `android`)
+   * Get a string (`linux`, `macos`, `windows`, `android`, or `ios`)
    * representing the operating system.
    */
   static String get operatingSystem => _operatingSystem;
@@ -115,6 +115,11 @@ class Platform {
   static final bool isAndroid = (_operatingSystem == "android");
 
   /**
+   * Returns true if the operating system is iOS.
+   */
+  static final bool isiOS = (_operatingSystem == "ios");
+
+  /**
    * Get the environment for this process.
    *
    * The returned environment is an unmodifiable map which content is