Add a WebDocument::watchCssSelectors(selectors)

Source/core/css/resolver/MatchedPropertiesCache.cpp

Index: Source/core/css/resolver/MatchedPropertiesCache.cpp
diff --git a/Source/core/css/resolver/MatchedPropertiesCache.cpp b/Source/core/css/resolver/MatchedPropertiesCache.cpp
index 17367953be4ece858b9713d5d91e0b28fd5c860b..d3c222a1f1ebd376142c9127f55921f6945042c6 100644
--- a/Source/core/css/resolver/MatchedPropertiesCache.cpp
+++ b/Source/core/css/resolver/MatchedPropertiesCache.cpp
@@ -148,6 +148,9 @@ bool MatchedPropertiesCache::isCacheable(const Element* element, const RenderSty
         return false;
     if (style->hasCurrentColor())
         return false;
+    // CSSPropertyInternalCallback sets the rule's selector name into the RenderStyle, and that's not recalculated if the RenderStyle is loaded from the cache, so don't cache it.
+    if (!style->callbackSelectors().isEmpty())
+        return false;
     // The cache assumes static knowledge about which properties are inherited.
     if (parentStyle->hasExplicitlyInheritedProperties())
         return false;