resolveScopedKeyframesRules should check @keyframes declared in shadow trees.

Source/core/css/resolver/ScopedStyleTree.cpp

Index: Source/core/css/resolver/ScopedStyleTree.cpp
diff --git a/Source/core/css/resolver/ScopedStyleTree.cpp b/Source/core/css/resolver/ScopedStyleTree.cpp
index 729faf15e8ff4603c139a9b8a43b29a0c722eff7..fe3f8a3d2cb031f689dde5679ab7c84a80743faf 100644
--- a/Source/core/css/resolver/ScopedStyleTree.cpp
+++ b/Source/core/css/resolver/ScopedStyleTree.cpp
@@ -138,6 +138,10 @@ void ScopedStyleTree::resolveScopedKeyframesRules(const Element* element, Vector
     TreeScope& treeScope = element->treeScope();
     bool applyAuthorStyles = treeScope.applyAuthorStyles();
 
+    // Add resolvers for shadow roots hosted by the given element.
+    collectScopedResolversForHostedShadowTrees(element, resolvers);
+
+    // Add resolvers while walking up DOM tree from the given element.
     for (ScopedStyleResolver* scopedResolver = scopedResolverFor(element); scopedResolver; scopedResolver = scopedResolver->parent()) {
         if (scopedResolver->treeScope() == treeScope || (applyAuthorStyles && scopedResolver->treeScope() == document))
             resolvers.append(scopedResolver);