Cache element docs (and add to completions) (#23694).

pkg/analysis_server/lib/src/services/completion/dart/suggestion_builder.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 services.completion.dart.suggestion.builder;
 
 import 'package:analysis_server/src/protocol_server.dart' as protocol;
 import 'package:analysis_server/src/protocol_server.dart'
     hide Element, ElementKind;
 import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
+import 'package:analysis_server/src/utilities/documentation.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/dart/element/visitor.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart';
 import 'package:path/path.dart' as path;
 
 const String DYNAMIC = 'dynamic';
 
 /**
@@ skipping 16 matching lines @@
   }
   bool isDeprecated = element.isDeprecated;
   CompletionSuggestion suggestion = new CompletionSuggestion(
       kind,
       isDeprecated ? DART_RELEVANCE_LOW : relevance,
       completion,
       completion.length,
       0,
       isDeprecated,
       false);
+
+  // Attach docs.
+  String doc = removeDartDocDelimiters(element.documentationComment);
+  suggestion.docComplete = doc;
+  suggestion.docSummary = getDartDocSummary(doc);
+
   suggestion.element = protocol.convertElement(element);
   Element enclosingElement = element.enclosingElement;
   if (enclosingElement is ClassElement) {
     suggestion.declaringType = enclosingElement.displayName;
   }
   suggestion.returnType = getReturnTypeString(element);
   if (element is ExecutableElement && element is! PropertyAccessorElement) {
     suggestion.parameterNames = element.parameters
         .map((ParameterElement parameter) => parameter.name)
         .toList();
@@ skipping 210 matching lines @@
   @override
   visitTopLevelVariableElement(TopLevelVariableElement element) {
     if (!typesOnly) {
       int relevance = element.library == containingLibrary
           ? DART_RELEVANCE_LOCAL_TOP_LEVEL_VARIABLE
           : DART_RELEVANCE_DEFAULT;
       addSuggestion(element, relevance: relevance);
     }
   }
 }