--- a/dom/animation/KeyframeEffect.cpp
+++ b/dom/animation/KeyframeEffect.cpp
@@ -92,17 +92,16 @@ KeyframeEffectReadOnly::KeyframeEffectRe
   AnimationEffectTimingReadOnly* aTiming)
   : AnimationEffectReadOnly(aDocument)
   , mTarget(aTarget)
   , mTiming(aTiming)
   , mPseudoType(aPseudoType)
   , mInEffectOnLastAnimationTimingUpdate(false)
 {
   MOZ_ASSERT(aTiming);
-  MOZ_ASSERT(aTarget, "null animation target is not yet supported");
 }
 
 JSObject*
 KeyframeEffectReadOnly::WrapObject(JSContext* aCx,
                                    JS::Handle<JSObject*> aGivenProto)
 {
   return KeyframeEffectReadOnlyBinding::Wrap(aCx, this, aGivenProto);
 }
@@ -732,38 +731,32 @@ KeyframeEffectReadOnly::ConstructKeyfram
   }
 
   TimingParams timingParams =
     TimingParams::FromOptionsUnion(aOptions, doc, aRv);
   if (aRv.Failed()) {
     return nullptr;
   }
 
-  if (aTarget.IsNull()) {
-    // We don't support null targets yet.
-    aRv.Throw(NS_ERROR_DOM_ANIM_NO_TARGET_ERR);
-    return nullptr;
-  }
-
-  const ElementOrCSSPseudoElement& target = aTarget.Value();
-  MOZ_ASSERT(target.IsElement() || target.IsCSSPseudoElement(),
-             "Uninitialized target");
-
   RefPtr<Element> targetElement;
   CSSPseudoElementType pseudoType = CSSPseudoElementType::NotPseudo;
-  if (target.IsElement()) {
-    targetElement = &target.GetAsElement();
-  } else {
-    targetElement = target.GetAsCSSPseudoElement().ParentElement();
-    pseudoType = target.GetAsCSSPseudoElement().GetType();
+  if (!aTarget.IsNull()) {
+    const ElementOrCSSPseudoElement& target = aTarget.Value();
+    MOZ_ASSERT(target.IsElement() || target.IsCSSPseudoElement(),
+               "Uninitialized target");
+    if (target.IsElement()) {
+      targetElement = &target.GetAsElement();
+    } else {
+      targetElement = target.GetAsCSSPseudoElement().ParentElement();
+      pseudoType = target.GetAsCSSPseudoElement().GetType();
+    }
   }
 
   RefPtr<KeyframeEffectType> effect =
-    new KeyframeEffectType(targetElement->OwnerDoc(), targetElement,
-                           pseudoType, timingParams);
+    new KeyframeEffectType(doc, targetElement, pseudoType, timingParams);
   effect->SetFrames(aGlobal.Context(), aFrames, aRv);
   if (aRv.Failed()) {
     return nullptr;
   }
 
   return effect.forget();
 }
 

--- a/dom/base/domerr.msg
+++ b/dom/base/domerr.msg
@@ -113,17 +113,16 @@ DOM4_MSG_DEF(BtParmInvalidError,  "Inval
 DOM4_MSG_DEF(BtUnhandledError,    "Unhandled",  NS_ERROR_DOM_BLUETOOTH_UNHANDLED)
 DOM4_MSG_DEF(BtAuthFailureError,  "Authentication failure",  NS_ERROR_DOM_BLUETOOTH_AUTH_FAILURE)
 DOM4_MSG_DEF(BtRmtDevDownError,   "Remote device down",  NS_ERROR_DOM_BLUETOOTH_RMT_DEV_DOWN)
 DOM4_MSG_DEF(BtAuthRejectedError, "Authentication rejected",  NS_ERROR_DOM_BLUETOOTH_AUTH_REJECTED)
 
 /* Web Animations errors */
 
 DOM4_MSG_DEF(NotSupportedError, "Animation to or from an underlying value is not yet supported.", NS_ERROR_DOM_ANIM_MISSING_PROPS_ERR)
-DOM4_MSG_DEF(NotSupportedError, "Animation with no target is not yet supported.", NS_ERROR_DOM_ANIM_NO_TARGET_ERR)
 DOM4_MSG_DEF(NotSupportedError, "Animation with no timeline is not yet supported.", NS_ERROR_DOM_ANIM_NO_TIMELINE_ERR)
 DOM4_MSG_DEF(NotSupportedError, "Animation with no effect is not yet supported.", NS_ERROR_DOM_ANIM_NO_EFFECT_ERR)
 
 /* common global codes (from nsError.h) */
 
 DOM_MSG_DEF(NS_OK                                  , "Success")
 DOM_MSG_DEF(NS_ERROR_NOT_INITIALIZED               , "Component not initialized")
 DOM_MSG_DEF(NS_ERROR_ALREADY_INITIALIZED           , "Component already initialized")

--- a/xpcom/base/ErrorList.h
+++ b/xpcom/base/ErrorList.h
@@ -948,19 +948,18 @@
   ERROR(NS_ERROR_SIGNED_APP_MANIFEST_INVALID,   FAILURE(1)),
 #undef MODULE
 
   /* ======================================================================= */
   /* 39: NS_ERROR_MODULE_DOM_ANIM */
   /* ======================================================================= */
 #define MODULE NS_ERROR_MODULE_DOM_ANIM
   ERROR(NS_ERROR_DOM_ANIM_MISSING_PROPS_ERR,              FAILURE(1)),
-  ERROR(NS_ERROR_DOM_ANIM_NO_TARGET_ERR,                  FAILURE(2)),
-  ERROR(NS_ERROR_DOM_ANIM_NO_TIMELINE_ERR,                FAILURE(3)),
-  ERROR(NS_ERROR_DOM_ANIM_NO_EFFECT_ERR,                  FAILURE(4)),
+  ERROR(NS_ERROR_DOM_ANIM_NO_TIMELINE_ERR,                FAILURE(2)),
+  ERROR(NS_ERROR_DOM_ANIM_NO_EFFECT_ERR,                  FAILURE(3)),
 #undef MODULE
 
   /* ======================================================================= */
   /* 40: NS_ERROR_MODULE_DOM_PUSH */
   /* ======================================================================= */
 #define MODULE NS_ERROR_MODULE_DOM_PUSH
   ERROR(NS_ERROR_DOM_PUSH_INVALID_REGISTRATION_ERR, FAILURE(1)),
   ERROR(NS_ERROR_DOM_PUSH_DENIED_ERR,               FAILURE(2)),