--- a/content/html/content/src/HTMLLegendElement.cpp
+++ b/content/html/content/src/HTMLLegendElement.cpp
@@ -1,14 +1,15 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/dom/HTMLLegendElement.h"
+#include "mozilla/dom/HTMLLegendElementBinding.h"
 #include "nsIDOMHTMLFormElement.h"
 #include "nsFocusManager.h"
 #include "nsIFrame.h"
 
 NS_IMPL_NS_NEW_HTML_ELEMENT(Legend)
 DOMCI_NODE_DATA(HTMLLegendElement, mozilla::dom::HTMLLegendElement)
 
 
@@ -165,10 +166,26 @@ void
 HTMLLegendElement::PerformAccesskey(bool aKeyCausesActivation,
                                     bool aIsTrustedEvent)
 {
   // just use the same behaviour as the focus method
   ErrorResult rv;
   Focus(rv);
 }
 
+already_AddRefed<nsHTMLFormElement>
+HTMLLegendElement::GetForm()
+{
+  Element* form = GetFormElement();
+  MOZ_ASSERT_IF(form, form->IsHTML(nsGkAtoms::form));
+  nsRefPtr<nsHTMLFormElement> ret = static_cast<nsHTMLFormElement*>(form);
+  return ret.forget();
+}
+
+JSObject*
+HTMLLegendElement::WrapNode(JSContext* aCx, JSObject* aScope,
+                            bool* aTriedToWrap)
+{
+  return HTMLLegendElementBinding::Wrap(aCx, aScope, this, aTriedToWrap);
+}
+
 } // namespace dom
 } // namespace mozilla

--- a/content/html/content/src/HTMLLegendElement.h
+++ b/content/html/content/src/HTMLLegendElement.h
@@ -3,16 +3,17 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef mozilla_dom_HTMLLegendElement_h
 #define mozilla_dom_HTMLLegendElement_h
 
 #include "nsIDOMHTMLLegendElement.h"
 #include "nsGenericHTMLElement.h"
+#include "nsHTMLFormElement.h"
 
 namespace mozilla {
 namespace dom {
 
 class HTMLLegendElement : public nsGenericHTMLElement,
                           public nsIDOMHTMLLegendElement
 {
 public:
@@ -71,17 +72,39 @@ public:
     nsCOMPtr<nsIFormControl> fieldsetControl = do_QueryInterface(GetFieldSet());
 
     return fieldsetControl ? fieldsetControl->GetFormElement() : nullptr;
   }
 
   virtual nsXPCClassInfo* GetClassInfo();
 
   virtual nsIDOMNode* AsDOMNode() { return this; }
+
+  /**
+   * WebIDL Interface
+   */
+
+  already_AddRefed<nsHTMLFormElement> GetForm();
+
+  // The XPCOM GetAlign is OK for us
+  void SetAlign(const nsAString& aAlign, ErrorResult& aError)
+  {
+    SetHTMLAttr(nsGkAtoms::align, aAlign, aError);
+  }
+
+  nsINode* GetParentObject() {
+    Element* form = GetFormElement();
+    return form ? static_cast<nsINode*>(form)
+                : nsGenericHTMLElement::GetParentObject();
+  }
+
 protected:
+  virtual JSObject* WrapNode(JSContext* aCx, JSObject* aScope,
+                             bool* aTriedToWrap) MOZ_OVERRIDE;
+
   /**
    * Get the fieldset content element that contains this legend.
    * Returns null if there is no fieldset containing this legend.
    */
   nsIContent* GetFieldSet();
 };
 
 } // namespace dom

new file mode 100644
--- /dev/null
+++ b/dom/webidl/HTMLLegendElement.webidl
@@ -0,0 +1,23 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * The origin of this IDL file is
+ * http://www.whatwg.org/specs/web-apps/current-work/#the-legend-element
+ * http://www.whatwg.org/specs/web-apps/current-work/#other-elements,-attributes-and-apis
+ *
+ * © Copyright 2004-2011 Apple Computer, Inc., Mozilla Foundation, and
+ * Opera Software ASA. You are granted a license to use, reproduce
+ * and create derivative works of this document.
+ */
+
+// http://www.whatwg.org/specs/web-apps/current-work/#the-legend-element
+interface HTMLLegendElement : HTMLElement {
+  readonly attribute HTMLFormElement? form;
+};
+
+// http://www.whatwg.org/specs/web-apps/current-work/#other-elements,-attributes-and-apis
+partial interface HTMLLegendElement {
+           attribute DOMString align;
+};

--- a/dom/webidl/WebIDL.mk
+++ b/dom/webidl/WebIDL.mk
@@ -73,16 +73,17 @@ webidl_files = \
   HTMLFontElement.webidl \
   HTMLFrameSetElement.webidl \
   HTMLHeadElement.webidl \
   HTMLHeadingElement.webidl \
   HTMLHRElement.webidl \
   HTMLHtmlElement.webidl \
   HTMLImageElement.webidl \
   HTMLLabelElement.webidl \
+  HTMLLegendElement.webidl \
   HTMLLIElement.webidl \
   HTMLLinkElement.webidl \
   HTMLMapElement.webidl \
   HTMLMetaElement.webidl \
   HTMLMeterElement.webidl \
   HTMLModElement.webidl \
   HTMLOListElement.webidl \
   HTMLOptGroupElement.webidl \