Tweak for escaping in instrumentation.

pkg/analyzer/lib/instrumentation/instrumentation.dart

 // Copyright (c) 2014, 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.
 
 library instrumentation;
 
 /**
  * The interface used by client code to communicate with an instrumentation
  * server.
  */
@@ skipping 117 matching lines @@
    * should be invoked on this instance after this method has been invoked.
    */
   void shutdown() {
     if (_instrumentationServer != null) {
       _instrumentationServer.shutdown();
       _instrumentationServer = null;
     }
   }
 
   /**
-   * Write an escaped version of the given [string] to the given [buffer].
+   * Write an escaped version of the given [field] to the given [buffer].
    */
   void _escape(StringBuffer buffer, String field) {
     int index = field.indexOf(':');
     if (index < 0) {
       buffer.write(field);
       return;
     }
     int start = 0;
-    while (index > 0) {
+    while (index >= 0) {
       buffer.write(field.substring(start, index));
       buffer.write('::');
       start = index + 1;
       index = field.indexOf(':', start);
     }
     buffer.write(field.substring(start));
   }
 
   /**
    * Return the result of joining the values of the given fields, escaping the
@@ skipping 21 matching lines @@
   /**
    * Convert the given [object] to a string.
    */
   String _toString(Object object) {
     if (object == null) {
       return 'null';
     }
     return object.toString();
   }
 }