Fix all strong mode errors and warnings.

test/mixin_test.dart

 // Copyright (c) 2013, 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 mixin_test;
 
+import 'package:csslib/src/messages.dart';
 import 'package:test/test.dart';
 
 import 'testing.dart';
 
 compileAndValidate(String input, String generated) {
-  var errors = [];
+  var errors = <Message>[];
   var stylesheet = compileCss(input, errors: errors, opts: options);
   expect(stylesheet != null, true);
   expect(errors.isEmpty, true, reason: errors.toString());
   expect(prettyPrint(stylesheet), generated);
 }
 
 compilePolyfillAndValidate(String input, String generated) {
-  var errors = [];
+  var errors = <Message>[];
   var stylesheet = polyFillCompileCss(input, errors: errors, opts: options);
   expect(stylesheet != null, true);
   expect(errors.isEmpty, true, reason: errors.toString());
   expect(prettyPrint(stylesheet), generated);
 }
 
 void topLevelMixin() {
   compileAndValidate(r'''
 @mixin silly-links {
   a {
@@ skipping 375 matching lines @@
   @include colors(@values);
 }
 ''', r'''.primary {
   color: #f00;
   background-color: #0f0;
   border-color: #00f;
 }''');
 }
 
 void badDeclarationInclude() {
-  final errors = [];
+  final errors = <Message>[];
   final input = r'''
 @mixin a {
   #foo-id {
     color: red;
   }
 }
 @mixin b {
   span {
     border: 2px dashed red;
     @include a;
   }
 }
 @include b;
 ''';
 
   var stylesheet = compileCss(input, errors: errors, opts: options);
 
   expect(stylesheet != null, true);
   expect(errors.isNotEmpty, true);
   expect(errors.length, 1, reason: errors.toString());
   var error = errors[0];
   expect(error.message, 'Using top-level mixin a as a declaration');
   expect(error.span.start.line, 8);
   expect(error.span.end.offset, 105);
 }
 
 void badTopInclude() {
-  final errors = [];
+  final errors = <Message>[];
   final input = r'''
 @mixin b {
   color: red;
 }
 
 @mixin a {
   span {
     border: 2px dashed red;
   }
   @include b;
 }
 
 @include a;
   ''';
 
   var stylesheet = compileCss(input, errors: errors, opts: options);
   expect(stylesheet != null, true);
   expect(errors.length, 1, reason: errors.toString());
   var error = errors[0];
   expect(error.message, 'Using declaration mixin b as top-level mixin');
   expect(error.span.start.line, 8);
   expect(error.span.end.offset, 90);
 }
 
 void emptyMixin() {
-  final errors = [];
+  final errors = <Message>[];
   final input = r'''
 @mixin a {
 }
 @mixin b {
   border: 2px dashed red;
   @include a;
 }
 div {
   @include b;
 }
   ''';
 
   var generated = r'''div {
   border: 2px dashed #f00;
 }''';
 
   var stylesheet = compileCss(input, errors: errors, opts: options);
 
   expect(stylesheet != null, true);
   expect(errors.isEmpty, true, reason: errors.toString());
   expect(prettyPrint(stylesheet), generated);
 }
 
 void undefinedTopLevel() {
-  final errors = [];
+  final errors = <Message>[];
   final input = r'''
 @mixin a {
   @include b;
 }
 @mixin b {
   span {
     border: 2px dashed red;
   }
   @include a;
 }
 
 @include b;
 
   ''';
 
   var stylesheet = compileCss(input, errors: errors, opts: options);
 
   expect(stylesheet != null, true);
   expect(errors.isNotEmpty, true);
   expect(errors.length, 1, reason: errors.toString());
   var error = errors[0];
   expect(error.message, 'Undefined mixin b');
   expect(error.span.start.line, 1);
   expect(error.span.start.offset, 14);
 }
 
 void undefinedDeclaration() {
-  final errors = [];
+  final errors = <Message>[];
   final input = r'''
 @mixin a {
   @include b;
 }
 @mixin b {
   border: 2px dashed red;
   @include a;
 }
 div {
   @include b;
@@ skipping 37 matching lines @@
 
 foo {
   @include a;
   @include a
 }
 ''', r'''foo {
   color: #f00;
   color: #f00;
 }''');
 
-  var errors = [];
+  var errors = <Message>[];
   var input = r'''
 @mixin a {
   foo { color: red }
 }
 
 @mixin b {
   @include a
   @include a
 }
 
@@ skipping 58 matching lines @@
     test('multiple args and var decls as args', mixinManyArgs);
   });
 
   group('Mixin warnings', () {
     test('undefined top-level', undefinedTopLevel);
     test('undefined declaration', undefinedDeclaration);
     test('detect bad top-level as declaration', badDeclarationInclude);
     test('detect bad declaration as top-level', badTopInclude);
   });
 }