Remove the checker and corresponding dead code

test/dependency_graph_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.
 
 library dev_compiler.test.dependency_graph_test;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:path/path.dart' as path;
@@ skipping 47 matching lines @@
     '/a10.dart': 'library a10;',
   };
 
   nodeOf(String filepath) => graph.nodeFromUri(new Uri.file(filepath));
 
   setUp(() {
     /// We completely reset the TestUriResolver to avoid interference between
     /// tests (since some tests modify the state of the files).
     testResourceProvider = createTestResourceProvider(testFiles);
     testUriResolver = new ResourceUriResolver(testResourceProvider);
-    context = createAnalysisContextWithSources(
-        options.strongOptions, options.sourceOptions,
+    context = createAnalysisContextWithSources(options.sourceOptions,
         fileResolvers: [testUriResolver]);
     graph = new SourceGraph(context, new LogReporter(context), options);
   });
 
   updateFile(Source source, [String newContents]) {
     var path = testResourceProvider.pathContext.fromUri(source.uri);
     if (newContents == null) newContents = source.contents.data;
     testResourceProvider.updateFile(path, newContents);
   }
 
@@ skipping 598 matching lines @@
           ''');
     });
   });
 
   group('server-mode', () {
     setUp(() {
       var opts = new CompilerOptions(
           runtimeDir: '/dev_compiler_runtime/',
           sourceOptions: new SourceResolverOptions(useMockSdk: true),
           serverMode: true);
-      context = createAnalysisContextWithSources(
-          opts.strongOptions, opts.sourceOptions,
+      context = createAnalysisContextWithSources(opts.sourceOptions,
           fileResolvers: [testUriResolver]);
       graph = new SourceGraph(context, new LogReporter(context), opts);
     });
 
     test('messages widget is automatically included', () {
       var node = nodeOf('/index3.html');
       expectGraph(
           node,
           '''
           index3.html
@@ skipping 458 matching lines @@
         var source = nodeOf('/bar.dart').source;
         updateFile(source, "hi");
         results = [];
         rebuild(node, buildWithTransitiveChange);
         expect(results, ['bar.dart', 'foo.dart']);
       });
     });
 
     group('null for non-existing files', () {
       setUp(() {
-        context = createAnalysisContextWithSources(
-            options.strongOptions, options.sourceOptions,
+        context = createAnalysisContextWithSources(options.sourceOptions,
             fileResolvers: [testUriResolver]);
         graph = new SourceGraph(context, new LogReporter(context), options);
       });
 
       test('recognize locally change between existing and not-existing', () {
         var n = nodeOf('/foo.dart');
         expect(n.source.exists(), isFalse);
         var source =
             testResourceProvider.newFile('/foo.dart', 'hi').createSource();
         expect(
@@ skipping 63 matching lines @@
   helper(node);
   return sb.toString();
 }
 
 final runtimeFilesWithoutPath = defaultRuntimeFiles
     .map((f) => f.replaceAll('dart/', ''))
     .toList(growable: false);
 final _RUNTIME_GRAPH = runtimeFilesWithoutPath.map((s) => '|--  $s').join('\n');
 final _RUNTIME_GRAPH_REBUILD =
     runtimeFilesWithoutPath.map((s) => '|--  $s [needs-rebuild]').join('\n');