Fixes for URI and Object completions with the new driver.

pkg/analysis_server/lib/src/provisional/completion/dart/completion_dart.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.
 
 library analysis_server.src.provisional.completion.completion_dart;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/provisional/completion/completion_core.dart';
@@ skipping 82 matching lines @@
    * This may be `null` if the library for a part file cannot be determined.
    */
   Source get librarySource;
 
   /**
    * Answer the [DartType] for Object in dart:core
    */
   DartType get objectType;
 
   /**
+   * Return the [SourceFactory] of the request.
+   */
+  SourceFactory get sourceFactory;
+
+  /**
    * Return the completion target.  This determines what part of the parse tree
    * will receive the newly inserted text.
    * At a minimum, all declarations in the completion scope in [target.unit]
    * will be resolved if they can be resolved.
    */
   CompletionTarget get target;
 
   /**
    * Return a [Future] that completes when the element associated with
    * the given [expression] in the target compilation unit is available.
@@ skipping 27 matching lines @@
   /**
    * Return a [Future] that completes with a list of [CompilationUnitElement]s
    * comprising the library in which in which the completion is occurring.
    * The [Future] may return `null` if the library unit cannot be determined
    * (e.g. unlinked part file).
    * Any information obtained from [target] prior to calling this method
    * should be discarded as it may have changed.
    */
   Future<List<CompilationUnitElement>> resolveUnits();
 }