Switch profiler from isolates to threads

runtime/vm/thread.h

Index: runtime/vm/thread.h
diff --git a/runtime/vm/thread.h b/runtime/vm/thread.h
index 61acb3240c3f810d474336ac3ed3d742c1da2d8d..3949916157628d8ccd2b2c5b7806a1e06c920067 100644
--- a/runtime/vm/thread.h
+++ b/runtime/vm/thread.h
@@ -371,6 +371,11 @@ LEAF_RUNTIME_ENTRY_LIST(DEFINE_OFFSET_METHOD)
     return id_;
   }
 
+  // Used to temporarily disable or enable thread interrupts.
+  void DisableThreadInterrupts();
+  void EnableThreadInterrupts();
+  bool ThreadInterruptsEnabled();
+
   void SetThreadInterrupter(ThreadInterruptCallback callback, void* data);
 
   bool IsThreadInterrupterEnabled(ThreadInterruptCallback* callback,
@@ -417,6 +422,7 @@ LEAF_RUNTIME_ENTRY_LIST(DEFINE_OFFSET_METHOD)
   const ThreadId id_;
   ThreadInterruptCallback thread_interrupt_callback_;
   void* thread_interrupt_data_;
+  uintptr_t thread_interrupt_disabled_;
   Isolate* isolate_;
   Heap* heap_;
   State state_;