CSSValue Immediates: Replace CSSPrimitiveValue usage with const references

Source/core/css/RuleFeature.cpp

Index: Source/core/css/RuleFeature.cpp
diff --git a/Source/core/css/RuleFeature.cpp b/Source/core/css/RuleFeature.cpp
index a53d9f3850c16d019ef7afbc94b60728caa95b7a..dda1f83551f52f199326e6248d8daf244f7ed678 100644
--- a/Source/core/css/RuleFeature.cpp
+++ b/Source/core/css/RuleFeature.cpp
@@ -305,7 +305,7 @@ void RuleFeatureSet::updateInvalidationSetsForContentAttribute(const RuleData& r
         return;
 
     StylePropertySet::PropertyReference contentProperty = propertySet.propertyAt(propertyIndex);
-    CSSValue contentValue = contentProperty.value();
+    const CSSValue& contentValue = contentProperty.value();
 
     if (!contentValue.isValueList())
         return;
@@ -313,7 +313,7 @@ void RuleFeatureSet::updateInvalidationSetsForContentAttribute(const RuleData& r
     for (auto& item : toCSSValueList(contentValue)) {
         if (!item.isPrimitiveValue())
             continue;
-        CSSPrimitiveValue primitiveItem = toCSSPrimitiveValue(item);
+        const CSSPrimitiveValue& primitiveItem = toCSSPrimitiveValue(item);
         if (!primitiveItem.isAttr())
             continue;
         ensureAttributeInvalidationSet(AtomicString(primitiveItem.getStringValue()));