Index test in generated animation list apply functions is wrong way r…

…ound

https://bugs.webkit.org/show_bug.cgi?id=265124
rdar://118644028

Reviewed by Tim Nguyen.

* Source/WebCore/css/process-css-properties.py:

We are adding unnecessary entries to the list and then later trimming them.

Canonical link: https://commits.webkit.org/270973@main

Source/WebCore/css/process-css-properties.py

@@ -3361,7 +3361,7 @@ def _generate_animation_property_value_setter(self, to, property):
         to.write(f"if (is<CSSValueList>(value)) {{")
         to.write(f"    // Walk each value and put it into an animation, creating new animations as needed.")
         to.write(f"    for (auto& currentValue : downcast<CSSValueList>(value)) {{")
-        to.write(f"        if (childIndex <= list.size())")
+        to.write(f"        if (childIndex >= list.size())")
         to.write(f"            list.append(Animation::create());")
         to.write(f"        builderState.styleMap().mapAnimation{property.name_for_methods}(list.animation(childIndex), currentValue);")
         to.write(f"        ++childIndex;")