Bug 1840732 Part 5: Remove unnecessary includes from accessible/aom, r=Jamie

This revision removes unnecessary include directives from cpp files in the
accessible/aom directory. These suggestions came from the Include What You Use
tool.

Depends on D182399

Differential Revision: https://phabricator.services.mozilla.com/D182400

Author: Nathan LaPre

accessible/aom/AccessibleNode.cpp

@@ -9,14 +9,11 @@
 #include "mozilla/dom/DOMStringList.h"
 #include "mozilla/StaticPrefs_accessibility.h"
 #include "nsContentUtils.h"
-#include "nsISimpleEnumerator.h"
 
-#include "AccAttributes.h"
 #include "LocalAccessible-inl.h"
 #include "nsAccessibilityService.h"
 #include "DocAccessible.h"
 
-#include "mozilla/dom/Document.h"  // for inline nsINode::GetParentObject
 #include "mozilla/dom/ToJSValue.h"
 
 using namespace mozilla;