Styling slot fallback content with ::slotted()

third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp

Index: third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp
diff --git a/third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp b/third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp
index d01e07d6aa636d0c5c3de42843fc1b684bca8102..2a744e3806ec6035b14decb9353c381f1f5da3da 100644
--- a/third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp
+++ b/third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp
@@ -267,8 +267,11 @@ static void MatchHostRules(const Element& element,
 static void MatchSlottedRules(const Element& element,
                               ElementRuleCollector& collector) {
   HTMLSlotElement* slot = element.AssignedSlot();
-  if (!slot)
-    return;
+  if (!slot) {
+    slot = HTMLSlotElement::FindFallbackSlotElementFor(element);
+    if (!slot)
+      return;
+  }
 
   HeapVector<Member<ScopedStyleResolver>> resolvers;
   for (; slot; slot = slot->AssignedSlot()) {