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

pkg/front_end/lib/src/fasta/source/outline_builder.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.outline_builder;
 
 import 'package:kernel/ast.dart' show ProcedureKind;
 
 import '../../scanner/token.dart' show Token;
 
@@ skipping 310 matching lines @@
     MethodBody kind = pop();
     List<FormalParameterBuilder> formals = pop();
     int formalsOffset = pop();
     List<TypeVariableBuilder> typeVariables = pop();
     int charOffset = pop();
     String name = pop();
     TypeBuilder returnType = pop();
     int modifiers =
         Modifier.validate(pop(), isAbstract: kind == MethodBody.Abstract);
     List<MetadataBuilder> metadata = pop();
+    String documentationComment = _getDocumentationComment(beginToken);
     checkEmpty(beginToken.charOffset);
     library.addProcedure(
+        documentationComment,
         metadata,
         modifiers,
         returnType,
         name,
         typeVariables,
         formals,
         computeProcedureKind(getOrSet),
         charOffset,
         formalsOffset,
         endToken.charOffset,
@@ skipping 79 matching lines @@
       name = nameOrOperator;
       kind = computeProcedureKind(getOrSet);
     }
     TypeBuilder returnType = pop();
     int modifiers =
         Modifier.validate(pop(), isAbstract: bodyKind == MethodBody.Abstract);
     if ((modifiers & externalMask) != 0) {
       modifiers &= ~abstractMask;
     }
     List<MetadataBuilder> metadata = pop();
+    String documentationComment = _getDocumentationComment(beginToken);
     library.addProcedure(
+        documentationComment,
         metadata,
         modifiers,
         returnType,
         name,
         typeVariables,
         formals,
         kind,
         charOffset,
         formalsOffset,
         endToken.charOffset,
@@ skipping 272 matching lines @@
     silenceParserErrors = true;
   }
 
   @override
   void endTopLevelFields(int count, Token beginToken, Token endToken) {
     debugEvent("endTopLevelFields");
     List fieldsInfo = popList(count * 4);
     TypeBuilder type = pop();
     int modifiers = Modifier.validate(pop());
     List<MetadataBuilder> metadata = pop();
-    library.addFields(metadata, modifiers, type, fieldsInfo);
+    String documentationComment = _getDocumentationComment(beginToken);
+    library.addFields(
+        documentationComment, metadata, modifiers, type, fieldsInfo);
     checkEmpty(beginToken.charOffset);
   }
 
   @override
   void endFields(int count, Token beginToken, Token endToken) {
     debugEvent("Fields");
     List fieldsInfo = popList(count * 4);
     TypeBuilder type = pop();
     int modifiers = Modifier.validate(pop());
     List<MetadataBuilder> metadata = pop();
-    library.addFields(metadata, modifiers, type, fieldsInfo);
+    String documentationComment = _getDocumentationComment(beginToken);
+    library.addFields(
+        documentationComment, metadata, modifiers, type, fieldsInfo);
   }
 
   @override
   void endTypeVariable(Token token, Token extendsOrSuper) {
     debugEvent("endTypeVariable");
     TypeBuilder bound = pop();
     int charOffset = pop();
     String name = pop();
     // TODO(paulberry): type variable metadata should not be ignored.  See
     // dartbug.com/28981.
@@ skipping 39 matching lines @@
     MethodBody kind = pop();
     ConstructorReferenceBuilder redirectionTarget;
     if (kind == MethodBody.RedirectingFactoryBody) {
       redirectionTarget = pop();
     }
     List<FormalParameterBuilder> formals = pop();
     int formalsOffset = pop();
     var name = pop();
     int modifiers = Modifier.validate(pop());
     List<MetadataBuilder> metadata = pop();
+    String documentationComment = _getDocumentationComment(beginToken);
     library.addFactoryMethod(
+        documentationComment,
         metadata,
         modifiers,
         name,
         formals,
         redirectionTarget,
         factoryKeyword.next.charOffset,
         formalsOffset,
         endToken.charOffset,
         nativeMethodName);
     nativeMethodName = null;
@@ skipping 130 matching lines @@
       docToken = docToken.next;
     }
     return buffer.toString();
   }
 
   @override
   void debugEvent(String name) {
     // printEvent(name);
   }
 }