Avoid reparsing keyframe selectors

Source/core/css/CSSParser.cpp

Index: Source/core/css/CSSParser.cpp
diff --git a/Source/core/css/CSSParser.cpp b/Source/core/css/CSSParser.cpp
index 63f4985f1b3bc2c8b5277d6e41a0f856b0f58336..5c055599f4e1d7e40ad91d6f7cb9e4d287e1b60a 100644
--- a/Source/core/css/CSSParser.cpp
+++ b/Source/core/css/CSSParser.cpp
@@ -11433,9 +11433,9 @@ void CSSParser::deleteFontFaceOnlyValues()
 
 StyleKeyframe* CSSParser::createKeyframe(CSSParserValueList* keys)
 {
-    // Create a key string from the passed keys
-    StringBuilder keyString;
-    for (unsigned i = 0; i < keys->size(); ++i) {
+    Vector<float> keyframeKeys;
+    size_t keyCount = keys->size();
+    for (size_t i = 0; i < keyCount; ++i) {
         ASSERT(keys->valueAt(i)->unit == CSSPrimitiveValue::CSS_NUMBER);
         float key = static_cast<float>(keys->valueAt(i)->fValue);
         if (key < 0 || key > 100) {
@@ -11445,14 +11445,12 @@ StyleKeyframe* CSSParser::createKeyframe(CSSParserValueList* keys)
             clearProperties();
             return 0;
         }
-        if (i != 0)
-            keyString.append(',');
-        keyString.append(String::number(key));
-        keyString.append('%');
+
+        keyframeKeys.append(key / 100);
     }
 
     RefPtr<StyleKeyframe> keyframe = StyleKeyframe::create();
-    keyframe->setKeyText(keyString.toString());
+    keyframe->setKeys(keyframeKeys);
     keyframe->setProperties(createStylePropertySet());
 
     clearProperties();