Special-case Timeline.{start,finish}Sync for Fuchsia

runtime/vm/vm_sources.gypi

 # Copyright (c) 2013, 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.
 
 # This file contains all sources (vm and tests) for the dart virtual machine.
 # Unit test files need to have a '_test' suffix appended to the name.
 {
   'sources': [
     'allocation.cc',
     'allocation.h',
@@ skipping 493 matching lines @@
     'thread_pool.cc',
     'thread_pool.h',
     'thread_pool_test.cc',
     'thread_registry.cc',
     'thread_registry.h',
     'thread_test.cc',
     'timeline.cc',
     'timeline.h',
     'timeline_analysis.cc',
     'timeline_analysis.h',
+    'timeline_android.cc',
+    'timeline_fuchsia.cc',
+    'timeline_linux.cc',
+    'timeline_macos.cc',
     'timeline_test.cc',
+    'timeline_win.cc',
     'timer.cc',
     'timer.h',
     'token.cc',
     'token.h',
     'token_position.cc',
     'token_position.h',
     'type_table.h',
     'unibrow.cc',
     'unibrow.h',
     'unibrow-inl.h',
@@ skipping 22 matching lines @@
     'weak_code.h',
     'weak_table.cc',
     'weak_table.h',
     'zone.cc',
     'zone.h',
     'zone_test.cc',
     'zone_text_buffer.cc',
     'zone_text_buffer.h',
   ],
 }