add RequestDatum tests and fix some situations

pkg/analysis_server/lib/src/protocol.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 protocol;
 
 import 'dart:convert' show JsonDecoder;
 
 /**
  * Instances of the class [Request] represent a request that was received.
@@ skipping 219 matching lines @@
    * Validate that the datum is a boolean (or a string that can be parsed
    * as a boolean), and return the bool.
    *
    * The value is typically the result of invoking either [getParameter] or
    * [getRequiredParameter].
    */
   bool asBool() {
     if (datum is bool) {
       return datum;
     } else if (datum == 'true') {
-      return datum == 'true';
+      return true;
     } else if (datum == 'false') {
-      return datum == 'false';
+      return false;
     }
     throw new RequestFailure(new Response.invalidParameter(request, datum,
         "be a boolean"));
   }
 
   /**
    * Validate that the datum is a string, and return it.
    */
   String asString() {
     if (datum is! String) {
@@ skipping 451 matching lines @@
   /**
    * The response to be returned as a result of the failure.
    */
   final Response response;
 
   /**
    * Initialize a newly created exception to return the given reponse.
    */
   RequestFailure(this.response);
 }