Fix race in debug assertion.

runtime/vm/thread.cc

 // 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.
 
 #include "vm/thread.h"
 
 #include "vm/isolate.h"
 #include "vm/os_thread.h"
 #include "vm/profiler.h"
 #include "vm/thread_interrupter.h"
@@ skipping 36 matching lines @@
   }
   SetCurrent(NULL);
 }
 
 
 void Thread::EnterIsolate(Isolate* isolate) {
   EnsureInit();
   Thread* thread = Thread::Current();
   ASSERT(thread->isolate() == NULL);
   ASSERT(isolate->mutator_thread() == NULL);
+  thread->isolate_ = isolate;
   isolate->set_mutator_thread(thread);
   // TODO(koda): Migrate thread_state_ and profile_data_ to Thread, to allow
   // helper threads concurrent with mutator.
   ASSERT(isolate->thread_state() == NULL);
   InterruptableThreadState* thread_state =
       ThreadInterrupter::GetCurrentThreadState();
 #if defined(DEBUG)
   Isolate::CheckForDuplicateThreadState(thread_state);
 #endif
   ASSERT(thread_state != NULL);
   Profiler::BeginExecution(isolate);
   isolate->set_thread_state(thread_state);
   isolate->set_vm_tag(VMTag::kVMTagId);
-  thread->isolate_ = isolate;
 }
 
 
 void Thread::ExitIsolate() {
   Thread* thread = Thread::Current();
   // TODO(koda): Audit callers; they should know whether they're in an isolate.
   if (thread == NULL) return;
   Isolate* isolate = thread->isolate();
   ASSERT(isolate != NULL);
   if (isolate->is_runnable()) {
@@ skipping 15 matching lines @@
   return isolate_->cha_;
 }
 
 
 void Thread::set_cha(CHA* value) {
   ASSERT(isolate_ != NULL);
   isolate_->cha_ = value;
 }
 
 }  // namespace dart