- Add assertions in MutexLocker/MonitorLocker to ensure that the code enclosed

runtime/vm/dart_api_impl.cc

 // 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.
 
 #include "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
 #include "lib/stacktrace.h"
@@ skipping 1592 matching lines @@
   ml.Notify();
 }
 
 
 DART_EXPORT Dart_Handle Dart_RunLoop() {
   Thread* T = Thread::Current();
   Isolate* I = T->isolate();
   CHECK_API_SCOPE(T);
   CHECK_CALLBACK_STATE(T);
   API_TIMELINE_BEGIN_END;
-  Monitor monitor;
-  MonitorLocker ml(&monitor);
+  // The message handler run loop does not expect to have a current isolate
+  // so we exit the isolate here and enter it again after the runloop is done.
+  ::Dart_ExitIsolate();
   {
-    // The message handler run loop does not expect to have a current isolate
-    // so we exit the isolate here and enter it again after the runloop is done.
-    Dart_ExitIsolate();
+    Monitor monitor;
+    MonitorLocker ml(&monitor);
     RunLoopData data;
     data.monitor = &monitor;
     data.done = false;
     I->message_handler()->Run(
         Dart::thread_pool(),
         NULL, RunLoopDone, reinterpret_cast<uword>(&data));
     while (!data.done) {
       ml.Wait();
     }
-    ::Dart_EnterIsolate(Api::CastIsolate(I));
   }
+  ::Dart_EnterIsolate(Api::CastIsolate(I));
   if (T->sticky_error() != Object::null()) {
     Dart_Handle error = Api::NewHandle(T, T->sticky_error());
     T->clear_sticky_error();
     return error;
   }
   if (FLAG_print_class_table) {
     HANDLESCOPE(T);
     I->class_table()->Print();
   }
   return Api::Success();
@@ skipping 4554 matching lines @@
   return Api::Success();
 }
 #endif  // DART_PRECOMPILER
 
 
 DART_EXPORT bool Dart_IsRunningPrecompiledCode() {
   return Dart::IsRunningPrecompiledCode();
 }
 
 }  // namespace dart