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..2b70616ac4e0246e6aff6539e43c58cd1b65ff6b 100644
--- a/Source/core/css/StylePropertySet.cpp
+++ b/Source/core/css/StylePropertySet.cpp
@@ -269,6 +269,16 @@ void MutableStylePropertySet::setProperty(CSSPropertyID propertyID, PassRefPtrWi
         m_propertyVector.append(CSSProperty(shorthand.properties()[i], value, important));
 }
 
+unsigned getIndexInShorthandVector(const CSSProperty& property)
+{
+    if (!property.isSetFromShorthand())
+        return 0;
+
+    Vector<StylePropertyShorthand, 4> shorthands;
+    getMatchingShorthandsForLonghand(property.id(), &shorthands);
+    return indexOfShorthandForLonghand(property.id(), shorthands);
+}
+
 bool MutableStylePropertySet::setProperty(const CSSProperty& property, CSSProperty* slot)
 {
     if (!removeShorthandProperty(property.id())) {
@@ -276,7 +286,12 @@ 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 (!property.isImportant() && toReplace->isImportant()) {
+                *toReplace = CSSProperty(property.id(), property.value(), false, property.isSetFromShorthand(), getIndexInShorthandVector(property), property.metadata().m_implicit);

[Timothy Loh, 2015/04/23 05:42:03]

Isn't this just the same as the other branch?

[sashab, 2015/04/23 05:59:05]

Oh, nice. Good point :D

+            } else {
+                *toReplace = property;
+            }
             return true;
         }
     }
@@ -314,10 +329,7 @@ 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