3 files changed, 40 insertions, 0 deletions
diff --git a/dom/base/Element.cpp b/dom/base/Element.cpp
index 52d06b0f8e..79b36a3149 100644
--- a/dom/base/Element.cpp
+++ b/dom/base/Element.cpp
@@ -1230,6 +1230,42 @@ Element::GetAttribute(const nsAString& aName, DOMString& aReturn)
   }
 }
 
+bool
+Element::ToggleAttribute(const nsAString& aName,
+                         const Optional<bool>& aForce,
+                         ErrorResult& aError)
+{
+  aError = nsContentUtils::CheckQName(aName, false);
+  if (aError.Failed()) {
+    return false;
+  }
+
+  nsAutoString nameToUse;
+  const nsAttrName* name = InternalGetAttrNameFromQName(aName, &nameToUse);
+  if (!name) {
+    if (aForce.WasPassed() && !aForce.Value()) {
+      return false;
+    }
+    nsCOMPtr<nsIAtom> nameAtom = NS_Atomize(nameToUse);
+    if (!nameAtom) {
+      aError.Throw(NS_ERROR_OUT_OF_MEMORY);
+      return false;
+    }
+    aError = SetAttr(kNameSpaceID_None, nameAtom, EmptyString(), true);
+    return true;
+  }
+  if (aForce.WasPassed() && aForce.Value()) {
+    return true;
+  }
+  // Hold a strong reference here so that the atom or nodeinfo doesn't go
+  // away during UnsetAttr. If it did UnsetAttr would be left with a
+  // dangling pointer as argument without knowing it.
+  nsAttrName tmp(*name);
+
+  aError = UnsetAttr(name->NamespaceID(), name->LocalName(), true);
+  return false;
+}
+
 void
 Element::SetAttribute(const nsAString& aName,
                       const nsAString& aValue,
diff --git a/dom/base/Element.h b/dom/base/Element.h
index 049984d1b8..c269ab14aa 100644
--- a/dom/base/Element.h
+++ b/dom/base/Element.h
@@ -686,6 +686,8 @@ public:
   void GetAttributeNS(const nsAString& aNamespaceURI,
                       const nsAString& aLocalName,
                       nsAString& aReturn);
+  bool ToggleAttribute(const nsAString& aName, const Optional<bool>& aForce,
+                       ErrorResult& aError);
   void SetAttribute(const nsAString& aName, const nsAString& aValue,
                     ErrorResult& aError);
   void SetAttributeNS(const nsAString& aNamespaceURI,
diff --git a/dom/webidl/Element.webidl b/dom/webidl/Element.webidl
index ca5f1b35cd..97eb4ffe0e 100644
--- a/dom/webidl/Element.webidl
+++ b/dom/webidl/Element.webidl
@@ -41,6 +41,8 @@ interface Element : Node {
   [Pure]
   DOMString? getAttributeNS(DOMString? namespace, DOMString localName);
   [Throws]
+  boolean toggleAttribute(DOMString name, optional boolean force);
+  [Throws]
   void setAttribute(DOMString name, DOMString value);
   [Throws]
   void setAttributeNS(DOMString? namespace, DOMString name, DOMString value);