Presentation API: ignore page visibility changes if ExecutionContext is destoyed.

Source/modules/presentation/PresentationAvailability.cpp

Index: Source/modules/presentation/PresentationAvailability.cpp
diff --git a/Source/modules/presentation/PresentationAvailability.cpp b/Source/modules/presentation/PresentationAvailability.cpp
index a9ce847dcf62bf2eb40e7d508f765c9c9cc225b6..17b5b0faa03873db0457d3773ed601e2498c13bc 100644
--- a/Source/modules/presentation/PresentationAvailability.cpp
+++ b/Source/modules/presentation/PresentationAvailability.cpp
@@ -103,6 +103,8 @@ void PresentationAvailability::stop()
 
 void PresentationAvailability::pageVisibilityChanged()
 {
+    if (m_state == State::Inactive)
+        return;
     updateListening();
 }
 
@@ -141,4 +143,4 @@ DEFINE_TRACE(PresentationAvailability)
     ActiveDOMObject::trace(visitor);
 }
 
-} // namespace
+} // blink namespace