expose strong checker API, for use by analyzer_cli

lib/src/summary.dart

 // Copyright (c) 2015, 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.
 
 /// Summary of error messages produced by a `SummaryReporter`.
 library dev_compiler.src.summary;
 
 import 'package:source_span/source_span.dart';
 
 /// Summary information computed by the DDC checker.
 abstract class Summary {
   Map toJsonMap();
 
   void accept(SummaryVisitor visitor);
 }
 
 /// Summary for the entire program.
 class GlobalSummary implements Summary {
-  /// Summary from the system libaries.
+  /// Summary from the system libraries.
   final Map<String, LibrarySummary> system = <String, LibrarySummary>{};
 
   /// Summary for libraries in packages.
   final Map<String, PackageSummary> packages = <String, PackageSummary>{};
 
   /// Summary for loose files
   // TODO(sigmund): consider inferring the package from the pubspec instead?
   final Map<String, IndividualSummary> loose = <String, IndividualSummary>{};
 
   GlobalSummary();
@@ skipping 183 matching lines @@
     }
   }
 
   void visitHtml(HtmlSummary html) {
     for (var msg in html.messages) {
       msg.accept(this);
     }
   }
   void visitMessage(MessageSummary message) {}
 }