Change to accommade Angular plugin and finalize removal of dependency to analysis_server

pkg/analyzer_plugin/lib/utilities/completion/completion_core.dart

 // Copyright (c) 2017, 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.
 
 import 'dart:async';
 
 import 'package:analyzer/dart/analysis/results.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
@@ skipping 28 matching lines @@
    * Set the offset of the region of text that should be replaced by the
    * selected completion suggestion.
    *
    * The offset can only be set once and applies to all of the suggestions.
    * Hence, this setter throws a [StateError] if the offset has already been
    * set.
    */
   void set offset(int offset);
 
   /**
+   * Indicates if the collector's offset has been set (and ultimately the
+   * length too).
+   */
+  bool get offsetIsSet;
+
+  /**
+   * Returns length of suggestions currently held.
+   */
+  int get suggestionsLength;
+
+  /**
    * Record the given completion [suggestion].
    */
   void addSuggestion(CompletionSuggestion suggestion);
 }
 
 /**
  * An object used to produce completion suggestions.
  *
  * Clients may implement this class when implementing plugins.
  */
@@ skipping 38 matching lines @@
           await contributor.computeSuggestions(request, collector);
         } catch (exception, stackTrace) {
           notifications.add(new PluginErrorParams(
                   false, exception.toString(), stackTrace.toString())
               .toNotification());
         }
       }
     } on AbortCompletion {
       return new GeneratorResult(null, notifications);
     }
+    collector.offset ??= request.offset;
+    collector.length ??= 0;
+
     CompletionGetSuggestionsResult result = new CompletionGetSuggestionsResult(
         collector.offset, collector.length, collector.suggestions);
     return new GeneratorResult(result, notifications);
   }
 }
 
 /**
  * The information about a requested list of completions.
  *
  * Clients may not extend, implement or mix-in this class.
@@ skipping 14 matching lines @@
    * The analysis result for the file in which the completion is being
    * requested.
    */
   ResolveResult get result;
 
   /**
    * Throw an [AbortCompletion] if the completion request has been aborted.
    */
   void checkAborted();
 }