Add a missing null check for MIDIAccess::getExecutionContext()

third_party/WebKit/Source/modules/webmidi/MIDIAccess.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 70 matching lines @@
 }
 
 void MIDIAccess::setOnstatechange(EventListener* listener)
 {
     m_hasPendingActivity = listener;
     setAttributeEventListener(EventTypeNames::statechange, listener);
 }
 
 bool MIDIAccess::hasPendingActivity() const
 {
-    return m_hasPendingActivity && !getExecutionContext()->activeDOMObjectsAreStopped();
+    return m_hasPendingActivity && getExecutionContext() && !getExecutionContext()->activeDOMObjectsAreStopped();
 }
 
 MIDIInputMap* MIDIAccess::inputs() const
 {
     HeapVector<Member<MIDIInput>> inputs;
     HashSet<String> ids;
     for (size_t i = 0; i < m_inputs.size(); ++i) {
         MIDIInput* input = m_inputs[i];
         if (input->getState() != PortState::MIDIPortStateDisconnected) {
             inputs.append(input);
@@ skipping 106 matching lines @@
 
 DEFINE_TRACE(MIDIAccess)
 {
     visitor->trace(m_inputs);
     visitor->trace(m_outputs);
     EventTargetWithInlineData::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 } // namespace blink