--- a/dom/ipc/TabParent.cpp
+++ b/dom/ipc/TabParent.cpp
@@ -1438,27 +1438,28 @@ TabParent::RecvPDocAccessibleConstructor
   }
 #endif
   return true;
 }
 
 a11y::DocAccessibleParent*
 TabParent::GetTopLevelDocAccessible() const
 {
+#ifdef ACCESSIBILITY
   // XXX Consider managing non top level PDocAccessibles with their parent
   // document accessible.
   const nsTArray<PDocAccessibleParent*>& docs = ManagedPDocAccessibleParent();
   size_t docCount = docs.Length();
   for (size_t i = 0; i < docCount; i++) {
     auto doc = static_cast<a11y::DocAccessibleParent*>(docs[i]);
     if (!doc->ParentDoc()) {
       return doc;
     }
   }
-
+#endif
   return nullptr;
 }
 
 PDocumentRendererParent*
 TabParent::AllocPDocumentRendererParent(const nsRect& documentRect,
                                         const gfx::Matrix& transform,
                                         const nsString& bgcolor,
                                         const uint32_t& renderFlags,

--- a/dom/ipc/TabParent.h
+++ b/dom/ipc/TabParent.h
@@ -34,19 +34,19 @@ class nsIFrameLoader;
 class nsIContent;
 class nsIPrincipal;
 class nsIURI;
 class nsILoadContext;
 class nsIDocShell;
 
 namespace mozilla {
 
-  namespace a11y {
+namespace a11y {
 class DocAccessibleParent;
-  }
+}
 
 namespace jsipc {
 class CpowHolder;
 } // namespace jsipc
 
 namespace layers {
 class AsyncDragMetrics;
 struct FrameMetrics;
@@ -261,17 +261,17 @@ public:
     virtual bool
     RecvPDocAccessibleConstructor(PDocAccessibleParent* aDoc,
                                   PDocAccessibleParent* aParentDoc,
                                   const uint64_t& aParentID) override;
 
     /**
      * Return the top level doc accessible parent for this tab.
      */
-     a11y::DocAccessibleParent* GetTopLevelDocAccessible() const;
+    a11y::DocAccessibleParent* GetTopLevelDocAccessible() const;
 
     void LoadURL(nsIURI* aURI);
     // XXX/cjones: it's not clear what we gain by hiding these
     // message-sending functions under a layer of indirection and
     // eating the return values
     void Show(const ScreenIntSize& size, bool aParentIsActive);
     void UpdateDimensions(const nsIntRect& rect, const ScreenIntSize& size);
     void UpdateFrame(const layers::FrameMetrics& aFrameMetrics);