Fix a number of editor errors and warnings in io tests

tests/standalone/src/io/SocketExceptionTest.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // Tests socket exceptions.
 
 #import("dart:isolate");
 #import("dart:io");
 
 class SocketExceptionTest {
@@ skipping 69 matching lines @@
       } catch (SocketIOException ex) {
         exceptionCaught = true;
       } catch (Exception ex) {
         wrongExceptionCaught = true;
       }
       Expect.equals(true, exceptionCaught);
       Expect.equals(true, !wrongExceptionCaught);
       exceptionCaught = false;
       try {
         List<int> buffer = new List<int>(42);
-        bool readDone = input.readInto(buffer, 0, 12);
+        input.readInto(buffer, 0, 12);
       } catch (SocketIOException ex) {
         exceptionCaught = true;
       } catch (Exception ex) {
         wrongExceptionCaught = true;
       }
       Expect.equals(true, exceptionCaught);
       Expect.equals(true, !wrongExceptionCaught);
       exceptionCaught = false;
       try {
         List<int> buffer = new List<int>(42);
@@ skipping 98 matching lines @@
     indexOutOfRangeExceptionTest();
     unknownHostTest();
     // TODO(sgjesse): This test seems to fail on the buildbot.
     //unresponsiveHostTest();
   }
 }
 
 main() {
   SocketExceptionTest.testMain();
 }