fix spelling in core libraries

sdk/lib/io/io_resource_info.dart

 // Copyright (c) 2015, 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.
 
 part of dart.io;
 
 abstract class _IOResourceInfo {
   final String type;
   final int id;
   String get name;
@@ skipping 33 matching lines @@
 
   // Not all call sites use this. In some cases, e.g., a socket, a read does
   // not always mean that we actually read some bytes (we may do a read to see
   // if there are some bytes available).
   void addRead(int bytes) {
     totalRead += bytes;
     readCount++;
     lastRead = _IOResourceInfo.timestamp;
   }
 
-  // In cases where we read but did not neccesarily get any bytes, use this to
+  // In cases where we read but did not necessarily get any bytes, use this to
   // update the readCount and timestamp. Manually update totalRead if any bytes
-  // where acutally read.
+  // where actually read.
   void didRead() { addRead(0); }
 
   void addWrite(int bytes) {
     totalWritten += bytes;
     writeCount++;
     lastWrite = _IOResourceInfo.timestamp;
   }
 
   _ReadWriteResourceInfo(String type) :
     totalRead = 0,
@@ skipping 205 matching lines @@
   static SocketOpened(_SocketResourceInfo info) {
     assert(!openSockets.containsKey(info.id));
     openSockets[info.id] = info;
   }
 
   static SocketClosed(_SocketResourceInfo info) {
     assert(openSockets.containsKey(info.id));
     openSockets.remove(info.id);
   }
 }