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

pkg/kernel/lib/binary/ast_to_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_to_binary;
 
 import '../ast.dart';
 import '../import_table.dart';
 import 'tag.dart';
 import 'dart:convert';
 import 'dart:typed_data';
@@ skipping 364 matching lines @@
       throw 'Missing canonical name for $node';
     }
     node.binaryOffset = _sink.flushedLength + _sink.length;
     writeByte(Tag.Class);
     writeCanonicalNameReference(getCanonicalNameOfClass(node));
     writeOffset(node.fileOffset);
     writeOffset(node.fileEndOffset);
     writeByte(flags);
     writeStringReference(node.name ?? '');
     writeUriReference(node.fileUri ?? '');
+    writeStringReference(node.documentationComment ?? '');
     writeAnnotationList(node.annotations);
     _typeParameterIndexer.enter(node.typeParameters);
     writeNodeList(node.typeParameters);
     writeOptionalNode(node.supertype);
     writeOptionalNode(node.mixedInType);
     writeNodeList(node.implementedTypes);
     writeNodeList(node.fields);
     writeNodeList(node.constructors);
     writeNodeList(node.procedures);
     _typeParameterIndexer.exit(node.typeParameters);
@@ skipping 952 matching lines @@
   visitCombinator(Combinator node) {
     node.names.forEach(put);
   }
 
   visitTypedef(Typedef node) {
     put(node.name);
     node.visitChildren(this);
   }
 
   visitClass(Class node) {
+    putOptional(node.documentationComment);
     putOptional(node.name);
     node.visitChildren(this);
   }
 
   visitNamedExpression(NamedExpression node) {
     put(node.name);
     node.visitChildren(this);
   }
 
   visitStringLiteral(StringLiteral node) {
@@ skipping 136 matching lines @@
     _sink.add(_buffer.sublist(0, length));
     _buffer = new Uint8List(SIZE);
     flushedLength += length;
     length = 0;
   }
 
   void flushAndDestroy() {
     _sink.add(_buffer.sublist(0, length));
   }
 }