Report iOS as iOS rather than OS X.

R=iposva@google.com

Review URL: https://codereview.chromium.org/1417013011 .

CHANGELOG.md

@@ -13,6 +13,10 @@
 * `dart:convert`
   * `Base64Decoder.convert` now takes optional `start` and `end` parameters.
 
+* `dart:io`
+  * `Platform` added an `isiOS` getter and `Platform.operatingSystem` may now
+    return `ios`.
+
 ## 1.13.0
 
 ### Core library changes

runtime/bin/platform_macos.cc

@@ -53,7 +53,11 @@ int Platform::NumberOfProcessors() {
 
 
 const char* Platform::OperatingSystem() {
+#if TARGET_OS_IOS
+  return "ios";
+#else
   return "macos";
+#endif
 }
 
 

runtime/vm/os_macos.cc

@@ -27,7 +27,11 @@
 namespace dart {
 
 const char* OS::Name() {
+#if TARGET_OS_IOS
+  return "ios";
+#else
   return "macos";
+#endif
 }
 
 

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;
@@ -114,6 +114,11 @@ 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.
    *