Parse documentation for class aliases, fix for /// comments.

pkg/front_end/lib/src/fasta/kernel/kernel_library_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.kernel_library_builder;
 
 import 'package:front_end/src/fasta/dill/dill_library_builder.dart';
 import 'package:front_end/src/fasta/import.dart';
 import 'package:kernel/ast.dart';
 
@@ skipping 253 matching lines @@
       addBuilder(name, builder, charOffset);
       if (!isNamed) {
         mixinApplicationClasses[name] = builder;
       }
     }
     return addNamedType(name, <KernelTypeBuilder>[], charOffset)
       ..bind(isNamed ? builder : null);
   }
 
   KernelTypeBuilder applyMixins(KernelTypeBuilder type,
-      {List<MetadataBuilder> metadata,
+      {String documentationComment,
+      List<MetadataBuilder> metadata,
       bool isSyntheticMixinImplementation: false,
       String name,
       String subclassName,
       List<TypeVariableBuilder> typeVariables,
       int modifiers: abstractMask,
       List<KernelTypeBuilder> interfaces,
       int charOffset: -1}) {
     if (type is KernelMixinApplicationBuilder) {
       subclassName ??= name;
       List<List<String>> signatureParts = <List<String>>[];
@@ skipping 162 matching lines @@
 
       if (name == null) {
         for (var type in mixin.arguments ?? const []) {
           type.bind(variables[type.name]);
         }
       }
       checkArguments(supertype);
       checkArguments(mixin);
 
       KernelNamedTypeBuilder t = applyMixin(supertype, mixin, signature,
+          documentationComment: documentationComment,
           metadata: metadata,
           name: name,
           isSyntheticMixinImplementation: isSyntheticMixinImplementation,
           typeVariables: typeVariables,
           modifiers: modifiers,
           interfaces: interfaces,
           charOffset: charOffset);
       if (name == null) {
         var builder = t.builder;
         t = addNamedType(
             t.name, freeTypes.keys.map((k) => freeTypes[k]).toList(), -1);
         if (builder != null) {
           t.bind(builder);
         }
       }
       return t;
     } else {
       return type;
     }
   }
 
   void addNamedMixinApplication(
+      String documentationComment,
       List<MetadataBuilder> metadata,
       String name,
       List<TypeVariableBuilder> typeVariables,
       int modifiers,
       KernelTypeBuilder mixinApplication,
       List<KernelTypeBuilder> interfaces,
       int charOffset) {
     // Nested declaration began in `OutlineBuilder.beginNamedMixinApplication`.
     endNestedDeclaration(name).resolveTypes(typeVariables, this);
     KernelNamedTypeBuilder supertype = applyMixins(mixinApplication,
+        documentationComment: documentationComment,
         metadata: metadata,
         name: name,
         typeVariables: typeVariables,
         modifiers: modifiers,
         interfaces: interfaces,
         charOffset: charOffset);
     checkTypeVariables(typeVariables, supertype.builder);
   }
 
   @override
@@ skipping 394 matching lines @@
           mixinApplicationClasses.putIfAbsent(name, () => builder);
       if (existing != builder) {
         part.scope.local.remove(name);
       }
     });
     super.includePart(part);
     nativeMethods.addAll(part.nativeMethods);
     boundlessTypeVariables.addAll(part.boundlessTypeVariables);
   }
 }