Make IOSink implement StringSink

tests/standalone/io/socket_exception_test.dart

Index: tests/standalone/io/socket_exception_test.dart
diff --git a/tests/standalone/io/socket_exception_test.dart b/tests/standalone/io/socket_exception_test.dart
index f2fec68924510ac6c1931122b1dd6e6038e430a5..3b83564f1ee730c3de52b8a794a97a1fe8232e27 100644
--- a/tests/standalone/io/socket_exception_test.dart
+++ b/tests/standalone/io/socket_exception_test.dart
@@ -88,7 +88,7 @@ class SocketExceptionTest {
         Expect.isFalse(wrongExceptionCaught);
         try {
           List<int> buffer = new List<int>(10);
-          client.add(buffer);
+          client.writeBytes(buffer);
         } on StateError catch (ex) {
           exceptionCaught = true;
         } catch (ex) {
@@ -121,7 +121,7 @@ class SocketExceptionTest {
       });
       Socket.connect("127.0.0.1", server.port).then((client) {
         client.listen((data) {}, onDone: server.close);
-        client.add(new List.filled(1024 * 1024, 0));
+        client.writeBytes(new List.filled(1024 * 1024, 0));
         client.destroy();
       });
     });
@@ -143,7 +143,7 @@ class SocketExceptionTest {
               Expect.equals(SIZE, count);
               server.close();
             });
-        client.add(new List.filled(SIZE, 0));
+        client.writeBytes(new List.filled(SIZE, 0));
         client.close();
         // Start piping now.
         completer.complete(null);
@@ -174,7 +174,7 @@ class SocketExceptionTest {
               Expect.isTrue(errors <= 1);
               server.close();
             });
-        client.add(new List.filled(SIZE, 0));
+        client.writeBytes(new List.filled(SIZE, 0));
         // Destroy other socket now.
         completer.complete(null);
         var port = new ReceivePort();
@@ -199,7 +199,7 @@ class SocketExceptionTest {
       Socket.connect("127.0.0.1", server.port).then((client) {
         const int SIZE = 1024 * 1024;
         int errors = 0;
-        client.add(new List.filled(SIZE, 0));
+        client.writeBytes(new List.filled(SIZE, 0));
         client.close();
         client.done.catchError((error) {
           server.close();