fix strong mode messages in pkg/dev_compiler

pkg/dev_compiler/test/codegen_test.dart

 // Copyright (c) 2016, 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.
 
 /// Tests code generation.
 ///
 /// Runs Dart Dev Compiler on all input in the `codegen` directory and checks
 /// that the output is what we expected.
 library dev_compiler.test.codegen_test;
 
 // TODO(rnystrom): This doesn't actually run any tests any more. It just
 // compiles stuff. This should be changed to not use unittest and just be a
 // regular program that outputs files.
 
 import 'dart:io' show Directory, File, Platform;
 import 'package:analyzer/analyzer.dart'
     show
         ExportDirective,
         ImportDirective,
         StringLiteral,
         UriBasedDirective,
         parseDirectives;
 import 'package:analyzer/src/generated/source.dart' show Source;
 import 'package:args/args.dart' show ArgParser, ArgResults;
 import 'package:dev_compiler/src/analyzer/context.dart' show AnalyzerOptions;
 import 'package:dev_compiler/src/compiler/compiler.dart'
     show BuildUnit, CompilerOptions, JSModuleFile, ModuleCompiler;
 import 'package:dev_compiler/src/compiler/module_builder.dart'
-    show
-        ModuleFormat,
-        addModuleFormatOptions,
-        parseModuleFormatOption,
-        pathToJSIdentifier;
+    show ModuleFormat, addModuleFormatOptions, parseModuleFormatOption;
 import 'package:path/path.dart' as path;
 import 'package:test/test.dart' show expect, isFalse, isTrue, test;
 
 import '../tool/build_sdk.dart' as build_sdk;
 import 'testing.dart' show repoDirectory, testDirectory;
 import 'multitest.dart' show extractTestsFromMultitest, isMultiTest;
 import 'not_yet_strong_tests.dart';
 
 final ArgParser argParser = new ArgParser()
   ..addOption('dart-sdk', help: 'Dart SDK Path', defaultsTo: null);
@@ skipping 281 matching lines @@
 /// Simplified from ParseDartTask.resolveDirective.
 String _resolveDirective(UriBasedDirective directive) {
   StringLiteral uriLiteral = directive.uri;
   String uriContent = uriLiteral.stringValue;
   if (uriContent != null) {
     uriContent = uriContent.trim();
     directive.uriContent = uriContent;
   }
   return directive.validate() == null ? uriContent : null;
 }