Reset the nesting level for setInterval after completion.

third_party/WebKit/Source/core/frame/DOMTimer.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 139 matching lines @@
   InspectorInstrumentation::AsyncTask asyncTask(context, this);
 
   // Simple case for non-one-shot timers.
   if (isActive()) {
     if (repeatInterval() && repeatInterval() < minimumInterval) {
       m_nestingLevel++;
       if (m_nestingLevel >= maxTimerNestingLevel)
         augmentRepeatInterval(minimumInterval - repeatInterval());
     }
 
+    // Get ExecutionContext early as it might be cleared during
+    // action->execute().
+    ExecutionContext* executionContext = getExecutionContext();
+
     // No access to member variables after this point, it can delete the timer.
     m_action->execute(context);
+
+    if (!executionContext)

[jochen (gone - plz use gerrit), 2017/02/15 10:35:12]

I don't think that's possible?

[Dan Elphick, 2017/02/15 14:03:32]

You're probably right - I was just playing it safe.

+      return;
+
+    executionContext->timers()->setTimerNestingLevel(0);
+
     return;
   }
 
   // Unregister the timer from ExecutionContext before executing the action
   // for one-shot timers.
   ScheduledAction* action = m_action.release();
   context->timers()->removeTimeoutByID(m_timeoutID);
 
   action->execute(context);
 
@@ skipping 16 matching lines @@
 RefPtr<WebTaskRunner> DOMTimer::timerTaskRunner() const {
   return getExecutionContext()->timers()->timerTaskRunner();
 }
 
 DEFINE_TRACE(DOMTimer) {
   visitor->trace(m_action);
   SuspendableTimer::trace(visitor);
 }
 
 }  // namespace blink