[fasta] Flip source flag and include source by default

pkg/front_end/lib/src/fasta/source/source_loader.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.
 
 library fasta.source_loader;
 
 import 'dart:async' show Future;
 
 import 'dart:io' show FileSystemException;
 
@@ skipping 28 matching lines @@
 import 'diet_listener.dart' show DietListener;
 
 import 'diet_parser.dart' show DietParser;
 
 import 'source_library_builder.dart' show SourceLibraryBuilder;
 
 import '../compiler_context.dart' show CompilerContext;
 
 class SourceLoader<L> extends Loader<L> {
   final Map<Uri, List<int>> sourceBytes = <Uri, List<int>>{};
-  final includeSource = CompilerContext.current.options.includeSource;
+  final excludeSource = CompilerContext.current.options.excludeSource;
 
   // Used when building directly to kernel.
   ClassHierarchy hierarchy;
   CoreTypes coreTypes;
 
   SourceLoader(TargetImplementation target) : super(target);
 
   Future<Token> tokenize(SourceLibraryBuilder library,
       {bool suppressLexicalErrors: false}) async {
     Uri uri = library.fileUri;
@@ skipping 25 matching lines @@
       String message = e.message;
       String osMessage = e.osError?.message;
       if (osMessage != null && osMessage.isNotEmpty) {
         message = osMessage;
       }
       return inputError(uri, -1, message);
     }
   }
 
   List<int> getSource(List<int> bytes) {
-    if (!includeSource) return const <int>[];
+    if (excludeSource) return const <int>[];
 
     // bytes is 0-terminated. We don't want that included.
     if (bytes is Uint8List) {
       return new Uint8List.view(
           bytes.buffer, bytes.offsetInBytes, bytes.length - 1);
     }
     return bytes.sublist(0, bytes.length - 1);
   }
 
   Future<Null> buildOutline(SourceLibraryBuilder library) async {
@@ skipping 249 matching lines @@
 
   void computeHierarchy(Program program) {
     hierarchy = new ClassHierarchy(program);
     ticker.logMs("Computed class hierarchy");
     coreTypes = new CoreTypes(program);
     ticker.logMs("Computed core types");
   }
 
   List<Uri> getDependencies() => sourceBytes.keys.toList();
 }