All strong mode cleaning of dart2js.

pkg/compiler/lib/src/js_backend/namer.dart

 // Copyright (c) 2011, 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 js_backend.namer;
 
 import 'dart:collection' show HashMap;
 
 import 'package:js_runtime/shared/embedded_names.dart' show JsGetName;
 
@@ skipping 1866 matching lines @@
       failed = true;
     } else {
       for (int i = 0; i < length; i++) {
         _visit(constant.entries[i]);
         if (failed) break;
       }
     }
   }
 
   @override
-  void visitMap(JavaScriptMapConstant constant, [_]) {
+  void visitMap(covariant JavaScriptMapConstant constant, [_]) {
     // TODO(9476): Incorporate type parameters into name.
     addRoot('Map');
     if (constant.length == 0) {
       add('empty');
     } else {
       // Using some bits from the keys hash tag groups the names Maps with the
       // same structure.
       add(getHashTag(constant.keyList, 2) + getHashTag(constant, 3));
     }
   }
@@ skipping 273 matching lines @@
   StringBuffer sb;
 
   FunctionTypeNamer(this.rtiEncoder);
 
   String computeName(ResolutionDartType type) {
     sb = new StringBuffer();
     visit(type);
     return sb.toString();
   }
 
-  visit(ResolutionDartType type, [_]) {
+  visit(covariant ResolutionDartType type, [_]) {
     type.accept(this, null);
   }
 
-  visitType(ResolutionDartType type, _) {
+  visitType(covariant ResolutionDartType type, _) {
     sb.write(type.name);
   }
 
-  visitFunctionType(ResolutionFunctionType type, _) {
+  visitFunctionType(covariant ResolutionFunctionType type, _) {
     if (rtiEncoder.isSimpleFunctionType(type)) {
       sb.write('args${type.parameterTypes.length}');
       return;
     }
     visit(type.returnType);
     sb.write('_');
     for (ResolutionDartType parameter in type.parameterTypes) {
       sb.write('_');
       visit(parameter);
     }
@@ skipping 39 matching lines @@
   void addSuggestion(String original, String suggestion) {
     assert(!_suggestedNames.containsKey(original));
     _suggestedNames[original] = suggestion;
   }
 
   bool hasSuggestion(String original) => _suggestedNames.containsKey(original);
   bool isSuggestion(String candidate) {
     return _suggestedNames.containsValue(candidate);
   }
 }