Use relative URIs for core library part-of statements.

sdk/lib/developer/timeline.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.
 
-part of dart.developer;
+part of "developer.dart";
 
 const bool _isProduct = const bool.fromEnvironment("dart.vm.product");
 
 typedef dynamic TimelineSyncFunction();
 typedef Future TimelineAsyncFunction();
 
 /// Add to the timeline.
 class Timeline {
   /// Start a synchronous operation labeled [name]. Optionally takes
   /// a [Map] of [arguments]. This operation must be finished before
@@ skipping 263 matching lines @@
 external void _reportTaskEvent(int start, int taskId, String phase,
     String category, String name, String argumentsAsJson);
 
 /// Reports a complete synchronous event.
 external void _reportCompleteEvent(int start, int startCpu, String category,
     String name, String argumentsAsJson);
 
 /// Reports an instant event.
 external void _reportInstantEvent(
     int start, String category, String name, String argumentsAsJson);