Prepare for development branch by updating externally-used API.

pkg/front_end/lib/src/fasta/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.loader;
 
 import 'dart:async' show Future;
 
 import 'dart:collection' show Queue;
 
@@ skipping 25 matching lines @@
   Loader(this.target);
 
   Ticker get ticker => target.ticker;
 
   /// Look up a library builder by the name [uri], or if such doesn't
   /// exist, create one. The canonical URI of the library is [uri], and its
   /// actual location is [fileUri].
   ///
   /// Canonical URIs have schemes like "dart", or "package", and the actual
   /// location is often a file URI.
-  LibraryBuilder read(Uri uri, [Uri fileUri]) {
+  LibraryBuilder read(Uri uri, int charOffset,
+      {Uri fileUri, LibraryBuilder accessor}) {

[ahe, 2017/05/23 15:04:24]

The accessor will be used to ensure that private dart libraries, such as
dart:_builtin can't be imported by user code.

[scheglov, 2017/05/23 16:14:45]

Please document new parameters.

[ahe, 2017/05/24 10:54:20]

Done.

     firstSourceUri ??= uri;
     LibraryBuilder builder = builders.putIfAbsent(uri, () {
       if (fileUri == null) {
         switch (uri.scheme) {
           case "package":
           case "dart":
             fileUri = target.translateUri(uri);
             break;
 
           default:
@@ skipping 10 matching lines @@
       if (library.loader == this) {
         unparsedLibraries.addLast(library);
       }
       return library;
     });
     return builder;
   }
 
   void ensureCoreLibrary() {
     if (coreLibrary == null) {
-      read(Uri.parse("dart:core"));
+      read(Uri.parse("dart:core"), -1);
       assert(coreLibrary != null);
     }
   }
 
   Future<Null> buildBodies() async {
     assert(coreLibrary != null);
     for (LibraryBuilder library in builders.values) {
       currentUriForCrashReporting = library.uri;
       await buildBody(library);
     }
@@ skipping 53 matching lines @@
   Builder getNativeAnnotation() => target.getNativeAnnotation(this);
 
   Builder getAbstractClassInstantiationError() {
     return target.getAbstractClassInstantiationError(this);
   }
 }
 
 String format(double d, int fractionDigits, int width) {
   return d.toStringAsFixed(fractionDigits).padLeft(width);
 }