Implement support for unprefixed keyframes rules resolution.

Source/core/css/resolver/ScopedStyleResolver.cpp

Index: Source/core/css/resolver/ScopedStyleResolver.cpp
diff --git a/Source/core/css/resolver/ScopedStyleResolver.cpp b/Source/core/css/resolver/ScopedStyleResolver.cpp
index 23f84234d924a71a3d85b168abef371d640d784e..261d45818bf572f1b9e2a3d52c0fb20d4156c60a 100644
--- a/Source/core/css/resolver/ScopedStyleResolver.cpp
+++ b/Source/core/css/resolver/ScopedStyleResolver.cpp
@@ -335,7 +335,15 @@ const StyleRuleKeyframes* ScopedStyleResolver::keyframeStylesForAnimation(const
 void ScopedStyleResolver::addKeyframeStyle(PassRefPtr<StyleRuleKeyframes> rule)
 {
     AtomicString s(rule->name());
-    m_keyframesRuleMap.set(s.impl(), rule);
+    if (rule->isVendorPrefixed()) {
+        KeyframesRuleMap::iterator it = m_keyframesRuleMap.find(rule->name().impl());
+        if (it == m_keyframesRuleMap.end())
+            m_keyframesRuleMap.set(s.impl(), rule);
+        else if (it->value->isVendorPrefixed())
+            m_keyframesRuleMap.set(s.impl(), rule);
+    } else {
+        m_keyframesRuleMap.set(s.impl(), rule);
+    }
 }
 
 inline RuleSet* ScopedStyleResolver::atHostRuleSetFor(const ShadowRoot* shadowRoot) const