| Index: src/isolate.h | 
| diff --git a/src/isolate.h b/src/isolate.h | 
| index be8141a37ba15e145601b04be08c7104915e9fe2..a4af1362a3c2fd80c4604c8caa6a97503aa3dd66 100644 | 
| --- a/src/isolate.h | 
| +++ b/src/isolate.h | 
| @@ -961,6 +961,8 @@ class Isolate { | 
|  | 
| void SetCurrentVMState(StateTag state) { | 
| if (RuntimeProfiler::IsEnabled()) { | 
| +      // Make sure thread local top is initialized. | 
| +      ASSERT(thread_local_top_.isolate_ == this); | 
| StateTag current_state = thread_local_top_.current_vm_state_; | 
| if (current_state != JS && state == JS) { | 
| // Non-JS -> JS transition. | 
|  |