Fix use-after-free in isolate reload.

runtime/vm/isolate.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 "vm/isolate.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 #include "platform/assert.h"
 #include "platform/text_buffer.h"
@@ skipping 1077 matching lines @@
   delete reload_context_;
   reload_context_ = NULL;
 }
 
 
 void Isolate::ReloadSources(bool test_mode) {
   ASSERT(!IsReloading());
   has_attempted_reload_ = true;
   reload_context_ = new IsolateReloadContext(this, test_mode);
   reload_context_->StartReload();
+  delete reload_context_;
+  reload_context_ = NULL;
 }
 #endif  // !PRODUCT
 
 
 void Isolate::DoneFinalizing() {
   NOT_IN_PRODUCT(
     if (IsReloading()) {
       reload_context_->FinishReload();
       if (reload_context_->has_error() && reload_context_->test_mode()) {
         // If the reload has an error and we are in test mode keep the reload
         // context on the isolate so that it can be used by unit tests.
         return;
       }
       if (reload_context_->has_error()) {
         // Remember the reload error.
         sticky_reload_error_ = reload_context_->error();
       }
       if (!reload_context_->has_error()) {
         reload_context_->ReportSuccess();
       }
-      delete reload_context_;
-      reload_context_ = NULL;
     }
   )
 }
 
 
 
 bool Isolate::MakeRunnable() {
   ASSERT(Isolate::Current() == NULL);
 
   MutexLocker ml(mutex_);
@@ skipping 1744 matching lines @@
 void IsolateSpawnState::DecrementSpawnCount() {
   ASSERT(spawn_count_monitor_ != NULL);
   ASSERT(spawn_count_ != NULL);
   MonitorLocker ml(spawn_count_monitor_);
   ASSERT(*spawn_count_ > 0);
   *spawn_count_ = *spawn_count_ - 1;
   ml.Notify();
 }
 
 }  // namespace dart