some fixes for --strong warnings

lib/src/analysis_context.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.
 
 library dev_compiler.src.analysis_context;
 
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/java_io.dart' show JavaFile;
 import 'package:analyzer/src/generated/sdk_io.dart' show DirectoryBasedDartSdk;
 import 'package:analyzer/src/generated/source.dart' show DartUriResolver;
 import 'package:analyzer/src/generated/source_io.dart';
 
 import 'package:dev_compiler/strong_mode.dart' show StrongModeOptions;
 
 import 'checker/resolver.dart';
 import 'dart_sdk.dart';
 import 'multi_package_resolver.dart';
 import 'options.dart';
 
 /// Creates an [AnalysisContext] with dev_compiler type rules and inference,
 /// using [createSourceFactory] to set up its [SourceFactory].
 AnalysisContext createAnalysisContextWithSources(
     StrongModeOptions strongOptions, SourceResolverOptions srcOptions,
-    {DartUriResolver sdkResolver, List fileResolvers}) {
+    {DartUriResolver sdkResolver, List<UriResolver> fileResolvers}) {
   var srcFactory = createSourceFactory(srcOptions,
       sdkResolver: sdkResolver, fileResolvers: fileResolvers);
   return createAnalysisContext(strongOptions)..sourceFactory = srcFactory;
 }
 
 /// Creates an analysis context that contains our restricted typing rules.
 AnalysisContext createAnalysisContext(StrongModeOptions options) {
   AnalysisContextImpl res = AnalysisEngine.instance.createAnalysisContext();
   enableDevCompilerInference(res, options);
   return res;
@@ skipping 13 matching lines @@
 /// to entirely override the DartUriResolver.
 ///
 /// If supplied, [fileResolvers] will override the default `file:` and
 /// `package:` URI resolvers.
 SourceFactory createSourceFactory(SourceResolverOptions options,
     {DartUriResolver sdkResolver, List<UriResolver> fileResolvers}) {
   var sdkResolver = options.useMockSdk
       ? createMockSdkResolver(mockSdkSources)
       : createSdkPathResolver(options.dartSdkPath);
 
-  var resolvers = [];
+  var resolvers = <UriResolver>[];
   if (options.customUrlMappings.isNotEmpty) {
     resolvers.add(new CustomUriResolver(options.customUrlMappings));
   }
   resolvers.add(sdkResolver);
   if (fileResolvers == null) fileResolvers = createFileResolvers(options);
   resolvers.addAll(fileResolvers);
   return new SourceFactory(resolvers);
 }
 
 List<UriResolver> createFileResolvers(SourceResolverOptions options) {
   return [
     new FileUriResolver(),
     options.useMultiPackage
         ? new MultiPackageResolver(options.packagePaths)
         : new PackageUriResolver([new JavaFile(options.packageRoot)])
   ];
 }
 
 /// Creates a [DartUriResolver] that uses a mock 'dart:' library contents.
 DartUriResolver createMockSdkResolver(Map<String, String> mockSources) =>
     new MockDartSdk(mockSources, reportMissing: true).resolver;
 
 /// Creates a [DartUriResolver] that uses the SDK at the given [sdkPath].
 DartUriResolver createSdkPathResolver(String sdkPath) => new DartUriResolver(
     new DirectoryBasedDartSdk(
         new JavaFile(sdkPath), /*useDart2jsPaths:*/ true));