Fix some issues with options handling

pkg/analyzer_cli/lib/src/options.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.
 
 import 'dart:io';
 
 import 'package:analyzer/file_system/physical_file_system.dart';
 import 'package:analyzer/src/command_line/arguments.dart';
 import 'package:analyzer/src/context/builder.dart';
 import 'package:analyzer_cli/src/ansi.dart' as ansi;
@@ skipping 207 matching lines @@
   bool get enableSuperMixins =>
       contextBuilderOptions.defaultOptions.enableSuperMixins;
 
   /// The path to a `.packages` configuration file
   String get packageConfigPath => contextBuilderOptions.defaultPackageFilePath;
 
   /// The path to the package root
   String get packageRootPath =>
       contextBuilderOptions.defaultPackagesDirectoryPath;
 
+  /// The source files to analyze
+  List<String> get sourceFiles => _sourceFiles;
+
+  /// Replace the sourceFiles parsed from the command line.
+  void rewriteSourceFiles(List<String> newSourceFiles) {
+    _sourceFiles = newSourceFiles;
+  }
+
   /// Parse [args] into [CommandLineOptions] describing the specified
   /// analyzer options. In case of a format error, calls [printAndFail], which
   /// by default prints an error message to stderr and exits.
   static CommandLineOptions parse(List<String> args,
       [printAndFail(String msg) = printAndFail]) {
     CommandLineOptions options = _parse(args);
     // Check SDK.
     if (!options.buildModePersistentWorker) {
       // Infer if unspecified.
       if (options.dartSdkPath == null) {
@@ skipping 49 matching lines @@
           options.buildSummaryUnlinkedInputs.isNotEmpty) {
         printAndFail('No summaries should be provided in combination with '
             '--build-summary-only-unlinked, they aren\'t needed.');
         return null; // Only reachable in testing.
       }
     }
 
     return options;
   }
 
-  /// The source files to analyze
-  List<String> get sourceFiles => _sourceFiles;
-
-  /// Replace the sourceFiles parsed from the command line.
-  void rewriteSourceFiles(List<String> newSourceFiles) {
-    _sourceFiles = newSourceFiles;
-  }
-
   static String _getVersion() {
     try {
       // This is relative to bin/snapshot, so ../..
       String versionPath =
           Platform.script.resolve('../../version').toFilePath();
       File versionFile = new File(versionPath);
       return versionFile.readAsStringSync().trim();
     } catch (_) {
       // This happens when the script is not running in the context of an SDK.
       return "<unknown>";
@@ skipping 162 matching lines @@
           defaultsTo: false,
           negatable: false,
           hide: hide)
       ..addFlag('enable_type_checks',
           help: 'Check types in constant evaluation.',
           defaultsTo: false,
           negatable: false,
           hide: hide)
       ..addFlag('enable-assert-initializers',
           help: 'Enable parsing of asserts in constructor initializers.',
-          defaultsTo: false,
+          defaultsTo: null,
           negatable: false,
           hide: hide)
       ..addFlag('use-analysis-driver-memory-byte-store',
           help: 'Use memory byte store, not the file system cache.',
           defaultsTo: false,
           negatable: false,
           hide: hide)
       ..addOption('url-mapping',
           help: '--url-mapping=libraryUri,/path/to/library.dart directs the '
               'analyzer to use "library.dart" as the source for an import '
@@ skipping 70 matching lines @@
         'Usage: $_binaryName [options...] <directory or list of files>');
     errorSink.writeln('');
     errorSink.writeln(parser.usage);
     errorSink.writeln('');
     errorSink.writeln('''
 Run "dartanalyzer -h -v" for verbose help output, including less commonly used options.
 For more information, see http://www.dartlang.org/tools/analyzer.
 ''');
   }
 }