Hide inference hints. Fixes #24563.

pkg/analyzer/test/src/task/strong/strong_test_helper.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.
 
 // TODO(jmesserly): this file needs to be refactored, it's a port from
 // package:dev_compiler's tests
 library test.src.task.strong.strong_test_helper;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
@@ skipping 45 matching lines @@
       if (key.startsWith(scheme)) {
         key = '/packages/${key.substring(scheme.length)}';
       }
       provider.newFile(key, value);
     });
     var uriResolver = new TestUriResolver(provider);
     // Enable task model strong mode
     AnalysisEngine.instance.useTaskModel = true;
     var context = AnalysisEngine.instance.createAnalysisContext();
     context.analysisOptions.strongMode = true;
+    context.analysisOptions.strongModeHints = true;
 
     context.sourceFactory = new SourceFactory([
       new MockDartSdk(mockSdkSources, reportMissing: true).resolver,
       uriResolver
     ]);
 
     // Run the checker on /main.dart.
     Source mainSource = uriResolver.resolveAbsolute(new Uri.file('/main.dart'));
     var initialLibrary =
         context.resolveCompilationUnit2(mainSource, mainSource);
@@ skipping 427 matching lines @@
   if (levelName == 'warning') return _MAGENTA_COLOR;
   if (levelName == 'info') return _CYAN_COLOR;
   return null;
 }
 
 const String _RED_COLOR = '\u001b[31m';
 const String _MAGENTA_COLOR = '\u001b[35m';
 const String _CYAN_COLOR = '\u001b[36m';
 const String GREEN_COLOR = '\u001b[32m';
 const String NO_COLOR = '\u001b[0m';