Collect samples during isolate startup

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 "platform/assert.h"
 #include "platform/json.h"
 #include "lib/mirrors.h"
@@ skipping 365 matching lines @@
     Profiler::EndExecution(old_current);
   }
   Thread::SetThreadLocal(isolate_key, reinterpret_cast<uword>(current));
   if (current != NULL) {
     ASSERT(current->thread_state() == NULL);
     InterruptableThreadState* thread_state =
         ThreadInterrupter::GetCurrentThreadState();
 #if defined(DEBUG)
     CheckForDuplicateThreadState(thread_state);
 #endif
+    ASSERT(thread_state != NULL);
     Profiler::BeginExecution(current);
     current->set_thread_state(thread_state);
     current->set_vm_tag(VMTag::kVMTagId);
   }
 }
 
 
 // The single thread local key which stores all the thread local data
 // for a thread. Since an Isolate is the central repository for
 // storing all isolate specific information a single thread local key
@@ skipping 771 matching lines @@
   return func.raw();
 }
 
 
 void IsolateSpawnState::Cleanup() {
   SwitchIsolateScope switch_scope(isolate());
   Dart::ShutdownIsolate();
 }
 
 }  // namespace dart