Re-collect rule features for watched selectors.

third_party/WebKit/Source/core/dom/StyleEngine.cpp

Index: third_party/WebKit/Source/core/dom/StyleEngine.cpp
diff --git a/third_party/WebKit/Source/core/dom/StyleEngine.cpp b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
index 11b0c7645a06a96d0478b57a1b440500e9764f5c..35d9e3a5428ced6a0c8421966dcfa41b7d576610 100644
--- a/third_party/WebKit/Source/core/dom/StyleEngine.cpp
+++ b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
@@ -246,6 +246,15 @@ void StyleEngine::modifiedStyleSheetCandidateNode(Node* node)
     resolverChanged(FullStyleUpdate);
 }
 
+void StyleEngine::watchedSelectorsChanged()
+{
+    if (m_resolver) {
+        m_resolver->initWatchedSelectorRules();
+        m_resolver->resetRuleFeatures();
+    }
+    document().setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::DeclarativeContent));
+}
+
 bool StyleEngine::shouldUpdateDocumentStyleSheetCollection(StyleResolverUpdateMode updateMode) const
 {
     return m_documentScopeDirty || updateMode == FullStyleUpdate;