diff --git a/accessible/base/TreeWalker.cpp b/accessible/base/TreeWalker.cpp
index 34f21d08a972..de3d1554690d 100644
--- a/accessible/base/TreeWalker.cpp
+++ b/accessible/base/TreeWalker.cpp
@@ -20,35 +20,19 @@ using namespace mozilla::a11y;
 // TreeWalker
 ////////////////////////////////////////////////////////////////////////////////
 
-TreeWalker::
-  TreeWalker(Accessible* aContext) :
-  mDoc(aContext->Document()), mContext(aContext), mAnchorNode(nullptr),
-  mChildFilter(nsIContent::eSkipPlaceholderContent), mFlags(0)
-{
-  mChildFilter |= mContext->NoXBLKids() ?
-    nsIContent::eAllButXBL | nsIContent::eAllChildren;
-
-  mAnchorNode = mContext->IsDoc() ?
-    mDoc->DocumentNode()->GetRootElement() : mContext->GetContent();
-
-  if (mAnchorNode) {
-    PushState(mAnchorNode);
-  }
-
-  MOZ_COUNT_CTOR(TreeWalker);
-}
-
 TreeWalker::
   TreeWalker(Accessible* aContext, nsIContent* aContent, uint32_t aFlags) :
   mDoc(aContext->Document()), mContext(aContext), mAnchorNode(aContent),
-  mChildFilter(nsIContent::eSkipPlaceholderContent), mFlags(aFlags)
+  mFlags(aFlags)
 {
-  MOZ_ASSERT(aContent, "No anchor node for the accessible tree walker");
+  NS_ASSERTION(aContent, "No node for the accessible tree walker!");
 
-  mChildFilter |= mContext->NoXBLKids() ?
-    nsIContent::eAllButXBL | nsIContent::eAllChildren;
+  mChildFilter = mContext->NoXBLKids() ?
+    nsIContent::eAllButXBL : nsIContent::eAllChildren;
+  mChildFilter |= nsIContent::eSkipPlaceholderContent;
 
-  PushState(aContent);
+  if (aContent)
+    PushState(aContent);
 
   MOZ_COUNT_CTOR(TreeWalker);
 }
diff --git a/accessible/base/TreeWalker.h b/accessible/base/TreeWalker.h
index c5fa8cae30ec..d35c8147ce15 100644
--- a/accessible/base/TreeWalker.h
+++ b/accessible/base/TreeWalker.h
@@ -33,20 +33,14 @@ public:
   };
 
   /**
-   * Used to navigate and create if needed the accessible children.
-   */
-  explicit TreeWalker(Accessible* aContext);
-
-  /**
-   * Used to navigate the accessible children relative to the anchor.
+   * Constructor
    *
    * @param aContext [in] container accessible for the given node, used to
    *                   define accessible context
-   * @param aAnchorNode [in] the node the search will be prepared relative to
+   * @param aNode    [in] the node the search will be prepared relative to
    * @param aFlags   [in] flags (see enum above)
    */
-  TreeWalker(Accessible* aContext, nsIContent* aAnchorNode, uint32_t aFlags = 0);
-
+  TreeWalker(Accessible* aContext, nsIContent* aNode, uint32_t aFlags = 0);
   ~TreeWalker();
 
   /**
diff --git a/accessible/generic/Accessible.cpp b/accessible/generic/Accessible.cpp
index da70dcaf65ae..960823ae5112 100644
--- a/accessible/generic/Accessible.cpp
+++ b/accessible/generic/Accessible.cpp
@@ -2541,9 +2541,10 @@ Accessible::LastRelease()
 void
 Accessible::CacheChildren()
 {
-  NS_ENSURE_TRUE_VOID(Document());
+  DocAccessible* doc = Document();
+  NS_ENSURE_TRUE_VOID(doc);
 
-  TreeWalker walker(this);
+  TreeWalker walker(this, mContent);
 
   Accessible* child = nullptr;
   while ((child = walker.Next()) && AppendChild(child));
diff --git a/accessible/generic/DocAccessible.cpp b/accessible/generic/DocAccessible.cpp
index ae610e353db3..49993d8c94b0 100644
--- a/accessible/generic/DocAccessible.cpp
+++ b/accessible/generic/DocAccessible.cpp
@@ -1418,6 +1418,25 @@ if (!aNode->IsContent() || !aNode->AsContent()->IsHTMLElement(nsGkAtoms::area))
   return GetAccessible(aNode);
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// Accessible protected
+
+void
+DocAccessible::CacheChildren()
+{
+  // Search for accessible children starting from the document element since
+  // some web pages tend to insert elements under it rather than document body.
+  dom::Element* rootElm = mDocumentNode->GetRootElement();
+  if (!rootElm)
+    return;
+
+  TreeWalker walker(this, rootElm);
+  Accessible* child = nullptr;
+  while ((child = walker.Next())) {
+    AppendChild(child);
+  }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Protected members
 
diff --git a/accessible/generic/DocAccessible.h b/accessible/generic/DocAccessible.h
index d889572c6315..d42af922203d 100644
--- a/accessible/generic/DocAccessible.h
+++ b/accessible/generic/DocAccessible.h
@@ -359,6 +359,9 @@ protected:
 
   void LastRelease();
 
+  // Accessible
+  virtual void CacheChildren() override;
+
   // DocAccessible
   virtual nsresult AddEventListeners();
   virtual nsresult RemoveEventListeners();