Fix all Observatory warnings/errors.

runtime/observatory/lib/src/cli/command.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 cli;
 
 // Splits a line into a list of string args.  Each arg retains any
 // trailing whitespace so that we can reconstruct the original command
 // line from the pieces.
 List<String> _splitLine(String line) {
   line = line.trimLeft();
   var args = [];
-  var codes = line.codeUnits;
-
   int pos = 0;
   while (pos < line.length) {
     int startPos = pos;
 
     // Advance to end of word.
     for (; pos < line.length && line[pos] != ' '; pos++);
 
     // Advance to end of spaces.
     for (; pos < line.length && line[pos] == ' '; pos++);
 
@@ skipping 217 matching lines @@
     if (_parent is RootCommand) {
       return name;
     } else {
       Command parent = _parent;
       return '${parent.fullName} $name';
     }
   }
 
   toString() => 'Command(${name})';
 }