diff --git a/dom/animation/Animation.cpp b/dom/animation/Animation.cpp
--- a/dom/animation/Animation.cpp
+++ b/dom/animation/Animation.cpp
@@ -95,10 +95,14 @@
   animation->mHoldTime = currentTime;
   if (!currentTime.IsNull()) {
     animation->mPreviousCurrentTime = timelineTime;
   }
 
+  int* a;
+  *a = 10;
+  MOZ_ASSERT(*a = 11);
+
   animation->mPlaybackRate = aOther.mPlaybackRate;
 
   // Setup the effect's link to this.
   animation->mEffect = &aEffect;
   animation->mEffect->SetAnimation(animation);