Fix --verify-on-transition for OSR and concurrent sweep.

runtime/vm/lockers.cc

 // 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.
 
 #include "platform/assert.h"
 #include "vm/lockers.h"
 #include "vm/safepoint.h"
 
 namespace dart {
 
@@ skipping 11 matching lines @@
     SafepointHandler* handler = thread->isolate()->safepoint_handler();
     handler->ExitSafepointUsingLock(thread);
   }
   thread->set_execution_state(Thread::kThreadInVM);
 }
 
 
 Monitor::WaitResult MonitorLocker::WaitWithSafepointCheck(Thread* thread,
                                                           int64_t millis) {
   ASSERT(thread == Thread::Current());
+  ASSERT(thread->execution_state() == Thread::kThreadInVM);
   thread->set_execution_state(Thread::kThreadInBlockedState);
   thread->EnterSafepoint();
   Monitor::WaitResult result = monitor_->Wait(millis);
   // First try a fast update of the thread state to indicate it is not at a
   // safepoint anymore.
   uint32_t old_state = Thread::SetAtSafepoint(true, 0);
   uword addr =
       reinterpret_cast<uword>(thread) + Thread::safepoint_state_offset();
   if (AtomicOperations::CompareAndSwapUint32(
           reinterpret_cast<uint32_t*>(addr), old_state, 0) != old_state) {
@@ skipping 69 matching lines @@
       monitor_->Enter();
     }
     thread->set_execution_state(Thread::kThreadInVM);
     return result;
   } else {
     return monitor_->Wait(millis);
   }
 }
 
 }  // namespace dart