Change stdout/stderr to binary mode on Windows

tests/standalone/io/stdio_nonblocking_test.dart

Index: tests/standalone/io/stdio_nonblocking_test.dart
diff --git a/tests/standalone/io/stdio_nonblocking_test.dart b/tests/standalone/io/stdio_nonblocking_test.dart
index 0740dbe7267291eef258543f25a2a6e8b34d7750..05f5fde4a2a17f0e7116271692ede3fcc8c4fcf4 100644
--- a/tests/standalone/io/stdio_nonblocking_test.dart
+++ b/tests/standalone/io/stdio_nonblocking_test.dart
@@ -17,12 +17,7 @@ void main() {
                   print(result.stdout);
                   print(result.stderr);
     Expect.equals(1, result.exitCode);
-    if (Platform.isWindows) {
-      Expect.equals('stdout\r\n\r\ntuodts\r\nABCDEFGHIJKLM\r\n', result.stdout);
-      Expect.equals('stderr\r\n\r\nrredts\r\nABCDEFGHIJKLM\r\n', result.stderr);
-    } else {
-      Expect.equals('stdout\n\ntuodts\nABCDEFGHIJKLM\n', result.stdout);
-      Expect.equals('stderr\n\nrredts\nABCDEFGHIJKLM\n', result.stderr);
-    }
+    Expect.equals('stdout\n\ntuodts\nABCDEFGHIJKLM\n', result.stdout);
+    Expect.equals('stderr\n\nrredts\nABCDEFGHIJKLM\n', result.stderr);
   });
 }