Fix recently introduced strong-mode errors

pkg/analyzer/test/source/embedder_test.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.
 
 @deprecated
 library analyzer.test.source.embedder_test;
 
 import 'dart:core';
 
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/source/embedder.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 import 'package:unittest/unittest.dart';
 
 import '../embedder_tests.dart';
 import '../resource_utils.dart';
 
 main() {
   defineReflectiveTests(DartUriResolverTest);
   defineReflectiveTests(EmbedderSdkTest);
   defineReflectiveTests(EmbedderUriResolverTest);
 }
 
 @reflectiveTest
 class DartUriResolverTest extends EmbedderRelatedTest {
   void test_embedderYaml() {
     EmbedderYamlLocator locator = new EmbedderYamlLocator({
-      'fox': [pathTranslator.getResource(foxLib)]
+      'fox': <Folder>[pathTranslator.getResource(foxLib)]
     });
     EmbedderSdk sdk = new EmbedderSdk(locator.embedderYamls);
     DartUriResolver resolver = new DartUriResolver(sdk);
 
     void expectResolved(dartUri, posixPath) {
       Source source = resolver.resolveAbsolute(Uri.parse(dartUri));
       expect(source, isNotNull, reason: dartUri);
       expect(source.fullName, posixToOSPath(posixPath));
     }
 
     // Check that they map to the correct paths.
     expectResolved('dart:core', '$foxLib/core.dart');
     expectResolved('dart:fox', '$foxLib/slippy.dart');
     expectResolved('dart:bear', '$foxLib/grizzly.dart');
     expectResolved('dart:relative', '$foxPath/relative.dart');
     expectResolved('dart:deep', '$foxLib/deep/directory/file.dart');
   }
 }
 
 @reflectiveTest
 class EmbedderSdkTest extends EmbedderRelatedTest {
   void test_creation() {
     EmbedderYamlLocator locator = new EmbedderYamlLocator({
-      'fox': [pathTranslator.getResource(foxLib)]
+      'fox': <Folder>[pathTranslator.getResource(foxLib)]
     });
     EmbedderSdk sdk = new EmbedderSdk(locator.embedderYamls);
 
     expect(sdk.urlMappings, hasLength(5));
   }
 
   void test_fromFileUri() {
     EmbedderYamlLocator locator = new EmbedderYamlLocator({
-      'fox': [pathTranslator.getResource(foxLib)]
+      'fox': <Folder>[pathTranslator.getResource(foxLib)]
     });
     EmbedderSdk sdk = new EmbedderSdk(locator.embedderYamls);
 
     expectSource(String posixPath, String dartUri) {
       Uri uri = Uri.parse(posixToOSFileUri(posixPath));
       Source source = sdk.fromFileUri(uri);
       expect(source, isNotNull, reason: posixPath);
       expect(source.uri.toString(), dartUri);
       expect(source.fullName, posixToOSPath(posixPath));
     }
 
     expectSource('$foxLib/slippy.dart', 'dart:fox');
     expectSource('$foxLib/deep/directory/file.dart', 'dart:deep');
     expectSource('$foxLib/deep/directory/part.dart', 'dart:deep/part.dart');
   }
 
   void test_getSdkLibrary() {
     EmbedderYamlLocator locator = new EmbedderYamlLocator({
-      'fox': [pathTranslator.getResource(foxLib)]
+      'fox': <Folder>[pathTranslator.getResource(foxLib)]
     });
     EmbedderSdk sdk = new EmbedderSdk(locator.embedderYamls);
 
     SdkLibrary lib = sdk.getSdkLibrary('dart:fox');
     expect(lib, isNotNull);
     expect(lib.path, posixToOSPath('$foxLib/slippy.dart'));
     expect(lib.shortName, 'dart:fox');
   }
 
   void test_mapDartUri() {
     EmbedderYamlLocator locator = new EmbedderYamlLocator({
-      'fox': [pathTranslator.getResource(foxLib)]
+      'fox': <Folder>[pathTranslator.getResource(foxLib)]
     });
     EmbedderSdk sdk = new EmbedderSdk(locator.embedderYamls);
 
     void expectSource(String dartUri, String posixPath) {
       Source source = sdk.mapDartUri(dartUri);
       expect(source, isNotNull, reason: posixPath);
       expect(source.uri.toString(), dartUri);
       expect(source.fullName, posixToOSPath(posixPath));
     }
 
     expectSource('dart:core', '$foxLib/core.dart');
     expectSource('dart:fox', '$foxLib/slippy.dart');
     expectSource('dart:deep', '$foxLib/deep/directory/file.dart');
     expectSource('dart:deep/part.dart', '$foxLib/deep/directory/part.dart');
   }
 }
 
 @reflectiveTest
 class EmbedderUriResolverTest extends EmbedderRelatedTest {
   void test_embedderYaml() {
     var locator = new EmbedderYamlLocator({
-      'fox': [pathTranslator.getResource(foxLib)]
+      'fox': <Folder>[pathTranslator.getResource(foxLib)]
     });
     var resolver = new EmbedderUriResolver(locator.embedderYamls);
 
     expectResolved(dartUri, posixPath) {
       Source source = resolver.resolveAbsolute(Uri.parse(dartUri));
       expect(source, isNotNull, reason: dartUri);
       expect(source.fullName, posixToOSPath(posixPath));
     }
 
     // We have five mappings.
     expect(resolver, hasLength(5));
     // Check that they map to the correct paths.
     expectResolved('dart:core', '$foxLib/core.dart');
     expectResolved('dart:fox', '$foxLib/slippy.dart');
     expectResolved('dart:bear', '$foxLib/grizzly.dart');
     expectResolved('dart:relative', '$foxPath/relative.dart');
     expectResolved('dart:deep', '$foxLib/deep/directory/file.dart');
   }
 
   void test_nullEmbedderYamls() {
     var resolver = new EmbedderUriResolver(null);
     expect(resolver, hasLength(0));
   }
 
   void test_restoreAbsolute() {
     var locator = new EmbedderYamlLocator({
-      'fox': [pathTranslator.getResource(foxLib)]
+      'fox': <Folder>[pathTranslator.getResource(foxLib)]
     });
     var resolver = new EmbedderUriResolver(locator.embedderYamls);
 
     expectRestore(String dartUri, [String expected]) {
       var parsedUri = Uri.parse(dartUri);
       var source = resolver.resolveAbsolute(parsedUri);
       expect(source, isNotNull);
       // Restore source's uri.
       var restoreUri = resolver.restoreAbsolute(source);
       expect(restoreUri, isNotNull, reason: dartUri);
       // Verify that it is 'dart:fox'.
       expect(restoreUri.toString(), expected ?? dartUri);
       List<String> split = (expected ?? dartUri).split(':');
       expect(restoreUri.scheme, split[0]);
       expect(restoreUri.path, split[1]);
     }
 
     expectRestore('dart:deep');
     expectRestore('dart:deep/file.dart', 'dart:deep');
     expectRestore('dart:deep/part.dart');
     expectRestore('dart:deep/deep/file.dart');
   }
 }