Fix server error messages

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:collection';
 import 'dart:convert';
 
 part 'generated_protocol.dart';
@@ skipping 576 matching lines @@
 
   RequestDecoder(this._request);
 
   RefactoringKind get refactoringKind {
     // Refactoring feedback objects should never appear in requests.
     return null;
   }
 
   @override
   dynamic mismatch(String jsonPath, String expected) {
-    return new RequestFailure(
-        new Response.invalidParameter(_request, jsonPath, 'be $expected'));
+    return new RequestFailure(new Response.invalidParameter(
+        _request, jsonPath, 'Expected to be $expected'));
   }
 
   @override
   dynamic missingKey(String jsonPath, String key) {
     return new RequestFailure(new Response.invalidParameter(
-        _request, jsonPath, 'contain key ${JSON.encode(key)}'));
+        _request, jsonPath, 'Expected to contain key ${JSON.encode(key)}'));
   }
 }
 
 /**
  * Instances of the class [RequestFailure] represent an exception that occurred
  * during the handling of a request that requires that an error be returned to
  * the client.
  */
 class RequestFailure implements Exception {
   /**
@@ skipping 296 matching lines @@
     hash = 0x1fffffff & (hash + ((0x03ffffff & hash) << 3));
     hash = hash ^ (hash >> 11);
     return 0x1fffffff & (hash + ((0x00003fff & hash) << 15));
   }
 
   static int hash2(a, b) => finish(combine(combine(0, a), b));
 
   static int hash4(a, b, c, d) =>
       finish(combine(combine(combine(combine(0, a), b), c), d));
 }