diff --git a/dom/animation/KeyframeEffect.cpp b/dom/animation/KeyframeEffect.cpp
index 79b0c2ecefa8..82973c07c8c5 100644
--- a/dom/animation/KeyframeEffect.cpp
+++ b/dom/animation/KeyframeEffect.cpp
@@ -2091,5 +2091,12 @@ KeyframeEffectReadOnly::ShouldBlockCompositorAnimations(const nsIFrame*
   return false;
 }
 
+JSObject*
+KeyframeEffect::WrapObject(JSContext* aCx,
+                           JS::Handle<JSObject*> aGivenProto)
+{
+  return KeyframeEffectBinding::Wrap(aCx, this, aGivenProto);
+}
+
 } // namespace dom
 } // namespace mozilla
diff --git a/dom/animation/KeyframeEffect.h b/dom/animation/KeyframeEffect.h
index 5a4a52b5f292..64a92b042a60 100644
--- a/dom/animation/KeyframeEffect.h
+++ b/dom/animation/KeyframeEffect.h
@@ -384,6 +384,19 @@ private:
   static const TimeDuration OverflowRegionRefreshInterval();
 };
 
+class KeyframeEffect : public KeyframeEffectReadOnly
+{
+public:
+  KeyframeEffect(nsIDocument* aDocument,
+                 Element* aTarget,
+                 nsCSSPseudoElements::Type aPseudoType,
+                 const TimingParams& aTiming)
+    : KeyframeEffectReadOnly(aDocument, aTarget, aPseudoType, aTiming) { }
+
+  JSObject* WrapObject(JSContext* aCx,
+                       JS::Handle<JSObject*> aGivenProto) override;
+};
+
 } // namespace dom
 } // namespace mozilla
 
diff --git a/dom/tests/mochitest/general/test_interfaces.html b/dom/tests/mochitest/general/test_interfaces.html
index 2ea01c169ce9..173f4a47d0c9 100644
--- a/dom/tests/mochitest/general/test_interfaces.html
+++ b/dom/tests/mochitest/general/test_interfaces.html
@@ -727,6 +727,8 @@ var interfaceNamesInGlobalScope =
     "KeyboardEvent",
 // IMPORTANT: Do not change this list without review from a DOM peer!
     {name: "KeyframeEffectReadOnly", release: false},
+// IMPORTANT: Do not change this list without review from a DOM peer!
+    {name: "KeyframeEffect", release: false},
 // IMPORTANT: Do not change this list without review from a DOM peer!
     "LocalMediaStream",
 // IMPORTANT: Do not change this list without review from a DOM peer!
diff --git a/dom/webidl/KeyframeEffect.webidl b/dom/webidl/KeyframeEffect.webidl
index 04786e46933f..d17c400ac427 100644
--- a/dom/webidl/KeyframeEffect.webidl
+++ b/dom/webidl/KeyframeEffect.webidl
@@ -4,7 +4,7 @@
  * You can obtain one at http://mozilla.org/MPL/2.0/.
  *
  * The origin of this IDL file is
- * http://w3c.github.io/web-animations/#the-keyframeeffect-interfaces
+ * https://w3c.github.io/web-animations/#the-keyframeeffect-interfaces
  *
  * Copyright © 2015 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C
  * liability, trademark and document use rules apply.
@@ -44,3 +44,21 @@ interface KeyframeEffectReadOnly : AnimationEffectReadOnly {
   // property-value pairs on the object.
   [Throws] sequence<object> getFrames();
 };
+
+
+// Bug 1211783 Implement KeyframeEffect constructor
+// [Constructor (Animatable? target,
+//               object? frames,
+//               optional (unrestricted double or KeyframeEffectOptions) options)]
+interface KeyframeEffect : KeyframeEffectReadOnly {
+  // Bug 1067769 - Allow setting KeyframeEffect.target
+  // inherit attribute Animatable?                 target;
+  // Bug 1216843 - implement animation composition
+  // inherit attribute IterationCompositeOperation iterationComposite;
+  // Bug 1216844 - implement additive animation
+  // inherit attribute CompositeOperation          composite;
+  // Bug 1244590 - implement spacing modes
+  // inherit attribute DOMString                   spacing;
+  // Bug 1244591 - implement setFrames
+  // void setFrames (object? frames);
+};