Add Member.documentationComment and use it to resynthesize documentation from Kernel.

pkg/front_end/lib/src/fasta/kernel/kernel_target.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 fasta.kernel_target;
 
 import 'dart:async' show Future;
 
 import 'package:kernel/ast.dart'
     show
@@ skipping 313 matching lines @@
     Uri uri = loader.first?.uri ?? Uri.parse("error:error");
     Uri fileUri = loader.first?.fileUri ?? uri;
     KernelLibraryBuilder library =
         new KernelLibraryBuilder(uri, fileUri, loader, false);
     loader.first = library;
     if (isFullProgram) {
       // If this is an outline, we shouldn't add an executable main
       // method. Similarly considerations apply to separate compilation. It
       // could also make sense to add a way to mark .dill files as having
       // compile-time errors.
-      KernelProcedureBuilder mainBuilder = new KernelProcedureBuilder(null, 0,
-          null, "main", null, null, ProcedureKind.Method, library, -1, -1, -1);
+      KernelProcedureBuilder mainBuilder = new KernelProcedureBuilder(
+          null,
+          null,
+          0,
+          null,
+          "main",
+          null,
+          null,
+          ProcedureKind.Method,
+          library,
+          -1,
+          -1,
+          -1);
       library.addBuilder(mainBuilder.name, mainBuilder, -1);
       mainBuilder.body = new Block(new List<Statement>.from(errors.map(
           (LocatedMessage message) => new ExpressionStatement(new Throw(
               new StringLiteral(context.format(message, Severity.error)))))));
     }
     library.build(loader.coreLibrary);
     return link(<Library>[library.library]);
   }
 
   /// Creates a program by combining [libraries] with the libraries of
@@ skipping 313 matching lines @@
   }
   for (Constructor constructor in superclass.constructors) {
     if (constructor.name.name.isEmpty) {
       return constructor.function.requiredParameterCount == 0
           ? constructor
           : null;
     }
   }
   return null;
 }