Guard against an isolate being scheduled twice

runtime/vm/profiler.h

 // 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.
 
 #ifndef VM_PROFILER_H_
 #define VM_PROFILER_H_
 
 #include "platform/hashmap.h"
 #include "platform/thread.h"
 #include "vm/allocation.h"
@@ skipping 23 matching lines @@
  private:
   static const intptr_t kMaxProfiledIsolates = 4096;
   static bool initialized_;
   static bool shutdown_;
   static Monitor* monitor_;
 
   static Isolate** isolates_;
   static intptr_t isolates_capacity_;
   static intptr_t isolates_size_;
 
+  static void ScheduleIsolateHelper(Isolate* isolate);
   static void ResizeIsolates(intptr_t new_capacity);
   static void AddIsolate(Isolate* isolate);
   static intptr_t FindIsolate(Isolate* isolate);
   static void RemoveIsolate(intptr_t i);
 
   // Returns the microseconds until the next live timer fires.
   static int64_t SampleAndRescheduleIsolates(int64_t current_time);
   static void FreeIsolateProfilingData(Isolate* isolate);
   static void ThreadMain(uword parameters);
 };
@@ skipping 136 matching lines @@
   const uintptr_t original_pc_;
   const uintptr_t original_fp_;
   const uintptr_t original_sp_;
   uintptr_t lower_bound_;
 };
 
 
 }  // namespace dart
 
 #endif  // VM_PROFILER_H_