Fix a number of editor errors and warnings in io tests

tests/standalone/src/io/StringStreamTest.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.
 
 #import("dart:io");
 
 void testUtf8() {
   List<int> data = [0x01,
                     0x7f,
                     0xc2, 0x80,
                     0xdf, 0xbf,
                     0xe0, 0xa0, 0x80,
                     0xef, 0xbf, 0xbf];
-  InputStream s = new ListInputStream();
+  ListInputStream s = new ListInputStream();
   s.write(data);
   s.markEndOfStream();
   StringInputStream stream = new StringInputStream(s);
   void stringData() {
     String s = stream.read();
     Expect.equals(6, s.length);
     Expect.equals(new String.fromCharCodes([0x01]), s[0]);
     Expect.equals(new String.fromCharCodes([0x7f]), s[1]);
     Expect.equals(new String.fromCharCodes([0x80]), s[2]);
     Expect.equals(new String.fromCharCodes([0x7ff]), s[3]);
     Expect.equals(new String.fromCharCodes([0x800]), s[4]);
     Expect.equals(new String.fromCharCodes([0xffff]), s[5]);
   }
   stream.onData = stringData;
 }
 
 void testLatin1() {
   List<int> data = [0x01,
                     0x7f,
                     0x44, 0x61, 0x72, 0x74,
                     0x80,
                     0xff];
-  InputStream s = new ListInputStream();
+  ListInputStream s = new ListInputStream();
   s.write(data);
   s.markEndOfStream();
   StringInputStream stream = new StringInputStream(s, Encoding.ISO_8859_1);
   void stringData() {
     String s = stream.read();
     Expect.equals(8, s.length);
     Expect.equals(new String.fromCharCodes([0x01]), s[0]);
     Expect.equals(new String.fromCharCodes([0x7f]), s[1]);
     Expect.equals("Dart", s.substring(2, 6));
     Expect.equals(new String.fromCharCodes([0x80]), s[6]);
     Expect.equals(new String.fromCharCodes([0xff]), s[7]);
   }
   stream.onData = stringData;
 }
 
 void testAscii() {
   List<int> data = [0x01,
                     0x44, 0x61, 0x72, 0x74,
                     0x7f];
-  InputStream s = new ListInputStream();
+  ListInputStream s = new ListInputStream();
   s.write(data);
   s.markEndOfStream();
   StringInputStream stream =
       new StringInputStream(s, Encoding.ASCII);
   void stringData() {
     String s = stream.read();
     Expect.equals(6, s.length);
     Expect.equals(new String.fromCharCodes([0x01]), s[0]);
     Expect.equals("Dart", s.substring(1, 5));
     Expect.equals(new String.fromCharCodes([0x7f]), s[5]);
   }
   stream.onData = stringData;
 }
 
 void testReadLine1() {
-  InputStream s = new ListInputStream();
+  ListInputStream s = new ListInputStream();
   StringInputStream stream = new StringInputStream(s);
   var stage = 0;
 
   void stringData() {
     var line;
     if (stage == 0) {
       line = stream.readLine();
       Expect.equals(null, line);
       stage++;
       s.markEndOfStream();
@@ skipping 10 matching lines @@
     Expect.equals(true, stream.closed);
     Expect.equals(2, stage);
   }
 
   stream.onData = stringData;
   stream.onClosed = streamClosed;
   s.write("Line".charCodes());
 }
 
 void testReadLine2() {
-  InputStream s = new ListInputStream();
+  ListInputStream s = new ListInputStream();
   StringInputStream stream = new StringInputStream(s);
   var stage = 0;
 
   void stringData() {
     var line;
     if (stage == 0) {
       Expect.equals(21, stream.available());
       line = stream.readLine();
       Expect.equals("Line1", line);
       Expect.equals(15, stream.available());
@@ skipping 43 matching lines @@
   void streamClosed() {
     Expect.equals(4, stage);
     Expect.equals(true, stream.closed);
   }
 
   stream.onLine = stringData;
   stream.onClosed = streamClosed;
   s.write("Line1\nLine2\r\nLine3\rLi".charCodes());
 }
 
-class TestException {
+class TestException implements Exception {
   TestException();
 }
 
 class ErrorInputStream implements InputStream {
   ErrorInputStream();
   List<int> read([int len]) => null;
   int readInto(List<int> buffer, [int offset, int len]) => 0;
   int available() => 0;
   void pipe(OutputStream output, [bool close]){ }
   void close() { }
@@ skipping 16 matching lines @@
 }
 
 main() {
   testUtf8();
   testLatin1();
   testAscii();
   testReadLine1();
   testReadLine2();
   testErrorHandler();
 }