[dart:io] Move Platform.ansiSupported to {Stdin,Stdout}.supportsAnsiEscapes

sdk/lib/_internal/js_runtime/lib/io_patch.dart

Index: sdk/lib/_internal/js_runtime/lib/io_patch.dart
diff --git a/sdk/lib/_internal/js_runtime/lib/io_patch.dart b/sdk/lib/_internal/js_runtime/lib/io_patch.dart
index d6647d7a37bfff7d13cf6b4b35c94c61f36b8e4c..3f60643f3de30b37cac448274f90d51a8a6e4a16 100644
--- a/sdk/lib/_internal/js_runtime/lib/io_patch.dart
+++ b/sdk/lib/_internal/js_runtime/lib/io_patch.dart
@@ -250,11 +250,6 @@ class _Platform {
   static String _version() {
     throw new UnsupportedError("Platform._version");
   }
-
-  @patch
-  static bool _ansiSupported() {
-    throw new UnsupportedError("Platform._ansiSupported");
-  }
 }
 
 @patch
@@ -550,6 +545,11 @@ class Stdin {
   void set lineMode(bool enabled) {
     throw new UnsupportedError("Stdin.lineMode");
   }
+
+  @patch
+  bool get ansiSupported {
+    throw new UnsupportedError("Stdin.ansiSupported");
+  }
 }
 
 @patch
@@ -568,6 +568,11 @@ class Stdout {
   int _terminalLines(int fd) {
     throw new UnsupportedError("Stdout.terminalLines");
   }
+
+  @patch
+  static bool _ansiSupported(int fd) {
+    throw new UnsupportedError("Stdout.ansiSupported");
+  }
 }
 
 @patch