LibWeb: Fix typos - act II

Author: https://github.com/szepeviktor
Commit: 5cc371d54c
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4264
Reviewed-by: https://github.com/AtkinsSJ ✅

Libraries/LibWeb/CSS/CSSAnimation.cpp

@@ -24,7 +24,7 @@ Optional<int> CSSAnimation::class_specific_composite_order(GC::Ref<Animations::A
 {
     auto other = GC::Ref { as<CSSAnimation>(*other_animation) };
 
-    // The existance of an owning element determines the animation class, so both animations should have their owning
+    // The existence of an owning element determines the animation class, so both animations should have their owning
     // element in the same state
     VERIFY(!owning_element() == !other->owning_element());