Remove Dart body for a native method.

lib/isolate/frog/isolateimpl.dart

 // Copyright (c) 2012, 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.
 
 /**
  * Concepts used here:
  *
  * "manager" - A manager contains one or more isolates, schedules their
  * execution, and performs other plumbing on their behalf.  The isolate
  * present at the creation of the manager is designated as its "root isolate".
@@ skipping 122 matching lines @@
   void _nativeDetectEnvironment() native @"""
     this.isWorker = $isWorker;
     this.supportsWorkers = $supportsWorkers;
     this.fromCommandLine = typeof(window) == 'undefined';
   """;
 
   void _nativeInitWorkerMessageHandler() native @"""
     $globalThis.onmessage = function (e) {
       _IsolateNatives._processWorkerMessage(this.mainManager, e);
     }
+  """;
+  /*: TODO: check that _processWorkerMessage is not discarded while treeshaking.
   """ {
     _IsolateNatives._processWorkerMessage(null, null);
   }
+  */
+
 
   /** Close the worker running this code if all isolates are done. */
   void maybeCloseWorker() {
     if (isolates.isEmpty()) {
       mainManager.postMessage(_serializeMessage({'command': 'close'}));
     }
   }
 }
 
 /** Context information tracked for each isolate. */
@@ skipping 477 matching lines @@
       'command': 'start2',
       'id': workerId,
       // Note: we serialize replyPort twice because the child worker needs to
       // first deserialize the worker id, before it can correctly deserialize
       // the port (port deserialization is sensitive to what is the current
       // workerId).
       'replyTo': _serializeMessage(replyPort),
       'functionName': functionName }));
   }
 }