Add documentationComment for Class to Kernel. Parse it. Resynthesize in Analyzer.

pkg/kernel/lib/binary/ast_from_binary.dart

 // Copyright (c) 2016, 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 kernel.ast_from_binary;
 
 import 'dart:convert';
 import 'dart:typed_data';
 
 import '../ast.dart';
 import '../transformations/flags.dart';
@@ skipping 452 matching lines @@
     node.fileEndOffset = readOffset();
     int flags = readByte();
     node.isAbstract = flags & 0x1 != 0;
     int levelIndex = (flags >> 1) & 0x3;
     var level = ClassLevel.values[levelIndex + 1];
     if (level.index >= node.level.index) {
       node.level = level;
     }
     var name = readStringOrNullIfEmpty();
     var fileUri = readUriReference();
+    var documentationComment = readStringOrNullIfEmpty();
     var annotations = readAnnotationList(node);
     debugPath.add(node.name ?? 'normal-class');
     readAndPushTypeParameterList(node.typeParameters, node);
     var supertype = readSupertypeOption();
     var mixedInType = readSupertypeOption();
     if (shouldWriteData) {
       _fillNonTreeNodeList(node.implementedTypes, readSupertype);
     } else {
       _skipNodeList(readSupertype);
     }
     _mergeNamedNodeList(node.fields, readField, node);
     _mergeNamedNodeList(node.constructors, readConstructor, node);
     _mergeNamedNodeList(node.procedures, readProcedure, node);
     typeParameterStack.length = 0;
     debugPath.removeLast();
     if (shouldWriteData) {
       node.name = name;
       node.fileUri = fileUri;
+      node.documentationComment = documentationComment;
       node.annotations = annotations;
       node.supertype = supertype;
       node.mixedInType = mixedInType;
     }
     return node;
   }
 
   int getAndResetTransformerFlags() {
     int flags = _transformerFlags;
     _transformerFlags = 0;
@@ skipping 738 matching lines @@
       ..fileOffset = offset
       ..fileEqualsOffset = fileEqualsOffset;
   }
 
   int readOffset() {
     // Offset is saved as unsigned,
     // but actually ranges from -1 and up (thus the -1)
     return readUInt() - 1;
   }
 }