Improve nomenclature of new AnalysisContext async method.

pkg/analysis_server/lib/src/services/completion/dart_completion_manager.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 services.completion.dart;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/completion/arglist_computer.dart';
@@ skipping 170 matching lines @@
       controller.close();
     }
   }
 
   /**
    * Return a future that either (a) completes with the resolved compilation
    * unit when analysis is complete, or (b) completes with null if the
    * compilation unit is never going to be resolved.
    */
   Future<CompilationUnit> waitForAnalysis() {
-    return context.getResolvedCompilationUnitFuture(
+    return context.computeResolvedCompilationUnitAsync(
         source,
         source).catchError((_) {
       // This source file is not scheduled for analysis, so a resolved
       // compilation unit is never going to get computed.
       return null;
     }, test: (e) => e is AnalysisNotScheduledError);
   }
 }
 
 /**
@@ skipping 79 matching lines @@
   _ReplacementOffsetBuilder(this.request) {
     request.replacementOffset = request.offset;
     request.replacementLength = 0;
   }
 
   visitSimpleIdentifier(SimpleIdentifier node) {
     request.replacementOffset = node.offset;
     request.replacementLength = node.length;
   }
 }