CSSStyleDeclaration::setProperty should override important style

Source/core/css/StylePropertySet.cpp

Index: Source/core/css/StylePropertySet.cpp
diff --git a/Source/core/css/StylePropertySet.cpp b/Source/core/css/StylePropertySet.cpp
index 310c2a543c87b6d3dad8f560b3fe8410f56ad5d3..364b46a2414787fa4bd19b7174da5ab13387b3c0 100644
--- a/Source/core/css/StylePropertySet.cpp
+++ b/Source/core/css/StylePropertySet.cpp
@@ -269,6 +269,17 @@ void MutableStylePropertySet::setProperty(CSSPropertyID propertyID, PassRefPtrWi
         m_propertyVector.append(CSSProperty(shorthand.properties()[i], value, important));
 }
 
+unsigned getIndexInShorthandVectorForPrefixingVariant(const CSSProperty& property, CSSPropertyID prefixingVariant)

[sashab, 2015/04/23 05:04:32]

This function existed before, but has been deleted. Is it needed for cloning the
CSSProperty fully?

+{
+    if (!property.isSetFromShorthand())
+        return 0;
+
+    CSSPropertyID prefixedShorthand = prefixingVariantForPropertyId(property.shorthandID());
+    Vector<StylePropertyShorthand, 4> shorthands;
+    getMatchingShorthandsForLonghand(prefixingVariant, &shorthands);
+    return indexOfShorthandForLonghand(prefixedShorthand, shorthands);
+}
+
 bool MutableStylePropertySet::setProperty(const CSSProperty& property, CSSProperty* slot)
 {
     if (!removeShorthandProperty(property.id())) {
@@ -276,7 +287,13 @@ bool MutableStylePropertySet::setProperty(const CSSProperty& property, CSSProper
         if (toReplace && *toReplace == property)
             return false;
         if (toReplace) {
-            *toReplace = property;
+            // Clear the important flag if the new property is not important
+            if (toReplace->isImportant() && !property.isImportant()) {
+                *toReplace = CSSProperty(property.id(), property.value(), false, property.isSetFromShorthand(), getIndexInShorthandVectorForPrefixingVariant(property, prefixingVariantForPropertyId(property.id())), property.metadata().m_implicit);
+            } else {
+                *toReplace = property;
+            }
+            setPrefixingVariantProperty(property);
             return true;
         }
     }
@@ -314,10 +331,7 @@ bool MutableStylePropertySet::addParsedProperties(const WillBeHeapVector<CSSProp
 
 bool MutableStylePropertySet::addParsedProperty(const CSSProperty& property)
 {
-    // Only add properties that have no !important counterpart present
-    if (!propertyIsImportant(property.id()) || property.isImportant())
-        return setProperty(property);
-    return false;
+    return setProperty(property);
 }
 
 String StylePropertySet::asText() const