Clean up dart:io exceptions.

sdk/lib/io/socket.dart

Index: sdk/lib/io/socket.dart
diff --git a/sdk/lib/io/socket.dart b/sdk/lib/io/socket.dart
index 040cf39424f06e9ae15935757477026970d4b65d..7164bf14408f26c7d3f7f40e2796811296b7ad8c 100644
--- a/sdk/lib/io/socket.dart
+++ b/sdk/lib/io/socket.dart
@@ -409,12 +409,12 @@ abstract class Socket implements Stream<List<int>>, IOSink {
 }
 
 
-class SocketIOException implements Exception {
-  const SocketIOException([String this.message = "",
-                           OSError this.osError = null]);
+class SocketException implements IOException {
+  const SocketException([String this.message = "",
+                         OSError this.osError = null]);
   String toString() {
     StringBuffer sb = new StringBuffer();
-    sb.write("SocketIOException");
+    sb.write("SocketException");
     if (!message.isEmpty) {
       sb.write(": $message");
       if (osError != null) {